They can run a business like that by making the barrier to switch providers very high, and the ease to collect bills very low. This is pretty much standard experience in the US. Even if one lives in a region where there are competitors, it's annoyingly difficult to switch providers so most just don't.

What is difficult about switching when theres actually competitors. I finally live in an area with multiple competitors and it was fairly painless.

Comcast tripled my bill for internet after one year and was also charging me for occasionally going over their data limit they set after I had been a customer for a couple months. I called Comcast and specified the day I wanted my service to end and had it coincide with the day I scheduled for RCN to connect my internet. The only annoying part was having to tell them more than once that there was no discount that would make me want to stay a customer since they were just going to pull the same crap in another year.

Part of the problem is that getting Comcast to close your account can be a craps shoot. For you, it worked just fine, like it does most of the time. For my mother, it was a nightmare.

My father passed away a few years back and my mother was trying to cut back on expenses, so she went to cancel the Comcast. The account was in my father's name, so she expected there to be some trouble. Comcast required that she bring in my father's death certificate. Also, they would be keeping the death certificate for their own records and a photocopy wouldn't do, so she'd need to go down to the county corner and get a second copy of the death certificate printed and hand signed. While this all seemed fairly onerous, I can at least appreciate the formality from an security standpoint.

After jumping through all of the hoops set forth by the Comcast, my mother drove out to the local branch office and presented the paperwork. The case worker brought didn't know how to handle the situation where someone had actually done everything that Comcast had asked and brought in the branch manager. He then told my mother that they needed my father to personally deliver his own death certificate before they would close the account.

What baffles me is that communications companies routinely complain that rolling a van and tech to anywhere is "expensive". They are willfully wasting money if what you say is true. I doubt that this is worth finding out who is their customer and who isn't.

Could it be the techs do it because they know there's a good chance they personally will be called out to fix it. Probably called out late at night, and collecting lots of overtime money?

They probably mean "expensive for the customer", not "expensive for us".

In order to get our current rate at a new building I had to send Comcast a copy of our bill. The bill they sent us.

Comcast knows who is on its network based upon the MAC address of the modem that is registered with your account when you sign up. It's not that simple to steal cable nowadays.

The problem is that the departments that handle infrastructure and contracts are probably divided, maybe even separate subsidiaries / companies. So the infrastructure subsidiary may not have enough information about who the actual customer is. All they see is equipment and maybe an assigned contract number, but no names. It gets worse, when infrastructure is done by contractors, just labeled as insert big telco here.

It's so easy to change a MAC address though.

Also in the past (different cable provider) they had it MAC authorised so I couldn't use my new modem. But then I set the new modem to use the MAC of the old one and it worked. So same

It's not as easy as it sounds. We're talking about the MAC address of the modem itself. In any current DOCSIS network you're going to need to use BPI+ which encrypts everything between the modem and the CMTS as well as authenticates the modem itself. Basically there's a cert on the modem that's signed by the manufacturer and the manufacturers cert is added to the CMTS. In short you can't just impersonate a modem and even just rooting a modem and getting at that certificate is difficult enough, not to mention once you do that you can only impersonate the modem that you've already rooted.

I'm not an expert by any means, but for VDSL2, I think you only need to get the DSL login data (username and password) and then your modem will work. I used a friend's login details when I bought a different modem and my provider didn't give me my DSL login. But it's all linked to the physical port on the DSLAM so that you cannot get faster speeds or anything like that.

The authentication in DSL is essentially an backward compatibility hack. Original motivation for that was compatibility with Radius/Diameter based AAA systems of ISPs (and to lesser extent the fact that the link the looks from both sides like faster dialup connection). Today it is used mostly because it is default. In many cases ISP (or even the underlying telco) either uses one login/password for all customers or simply accepts anything.

All DSL lines have same L2 interface as ATM and thus there is no authentication. How the authentication works is that PPP gets tunelled through this, either by running PPP directly on AAL5 (PPPoA), or more commonly and somewhat nonsensically by tuneling by wrapping PPP in ethernet frames that are then transfered inside AAL5 channel (PPPoE, or more correctly PPPoEoA). Interestingly this is usually used only on the first virtual channel (ie. the "Internet" one) and not on the additional channels that you typically get today (IPTV, VoIP, free hotspots...), these additional channels are usually straight Ethernet over AAL5 with the modem behaving like simple L2 bridge (often these channels form relatively large broadcast domains that are typically NATed to the Internet).

[Edit:] In contrast, DOCSIS variants for Internet over CaTV are derived directly from IEEE 802 family of technologies and there are no telco-style ATM/X.25/whatever protocols in between. Good first approximation is that the DOCSIS segment handled by one CMTS behaves like one big ethernet switch. But beacuse of the nature of shared medium, data on the coaxial cable is encrypted as otherwise it would be trivial to eavesdrop on anyone else on the same segment. The encryption even involves PKI to mutually authenticate modem and CMTS.

On DSL there is clear physical interface on the network side, that can be turned on or off, shaped and metered which is everything that the ISP cares about from the charging and authentication PoV. CaTV does not have anything like that and thus there has to be relative complex authentication and confidentiality mechanism (that is, somewhat paradoxically, usually completely invisible to the end user).

Yea but if you change your MAC address to an unregistered one (what happened when you connected a new modem) you won't get internet and if you change it to a duplicate one your account will be suspended (unless you're doing a swap like in your case). You can't have 2 modems using the same MAC simultaneously.

In the days of analog you could connect a walmart cable to the box outside, and your TV would receive cable. The cable box probably had an empty connection on the splitter outside to plug the cable into, and opening the box isn't hard so this entire process was well in the ability of anyone who could change their oil. There were plenty of bootleg instructions on how to bypass the scrambling system to get any channel, though the basic cable channels were not scrambled in the first place.

Infrastructure is probably handled by a different department, maybe even a different subsidiary or company. I bet, the infrastructure people get to see as less information as possible about the contract / actual customer and no information about other lines / contracts.

I worked on workforce management software for utilities companies. The field crews often only see information about their current task for various reasons (data size of standing data, privacy protection, field crew is a contractor).

It isn't that they have no way of knowing, it just isn't worth the tech's time (in their mind) to validate the status of every connection. If they are like most other telecoms, they would have to manually cross reference date from multiple applications.