The main reason for this is so that different wattage power supplies can be used with the same connector. The laptop determines the power supply type to see if it can safely draw its full load.
USB-C takes this one step further by having a full negotiation process before supplying any of a number of voltage / wattage levels.
I suppose the key question is: Does it identify the device and then decide not to work with non-Dell devices? It's fine to read required information, but unnecessarily constraining what happens based on that information brings it back to DRM.
The power supply is "constant current, constant voltage" - ie. it is 19 volts for all currents under 3 amps, but if you try to exceed 3 amps, it will supply exactly 3 amps at whatever voltage that works out to.
The benefit of this scheme is it's super easy to implement on both sides, and fully universal - the device just keeps increasing the current draw till the voltage starts to drop, and it then knows it's hit the limit. The device doesn't need any kind of logic at all - a dumb light bulb will either work if there is enough power, or not work if there isn't, but nothing will get damaged.
It's also compatible with Y splitters - so you can plug in two laptops to the supply, with no extra electronics, and both can share the power. (there is no guarantee of even power splitting tho!)
A big benefit is the power supply can have fully variable capabilities - for example, most power supplies are thermal limited, and on a cold day it could offer slightly more current to charge your battery slightly faster - all without any digital logic, protocols, or anything manufacturer specific.
Anything more complex with sense resistors, ID chips, extra wires, etc. just costs more, and provides less utility, and almost looks like a deliberate attempt to reduce compatibility and increase sales of chargers.
The resistor setup is both simpler, and unlike the memory chip, can't easily be repurposed for DRM.
With USB type-c chargers it became more or less redundant although the USB type-c power spec implementation is all over the place with many cables and chargers on the market capable of ruining your devices completely.
This isn’t as much of a DRM as a reliability measure if you are going to use cheap power adapters you are quite likely to be able to ruin your laptop.
There are plenty of 3rd party adapters that can send the correct signal to a Dell laptop, those who can’t usually will power the system but not charge the battery simultaneously.
With USB type-C many adapters would charge the laptop at 60W instead of the 100-130W that original Dell adapters can, some of the certified USB type-c docking stations/adapters would be able to charge it at full rate if they are actually capable of delivering the current required.
Not everything is done because vendors want to lock you in, laptops now are smaller and power hungrier than ever and people want to charge their laptops at full rate with cables that could barely charge a phone.
With USB-C things will mostly work but will work slower I can charge my MBP 15” with my Nintendo Switch power adapter it will just take longer and likely will cause the Switch adapter to die the few times I had to do it I’ve noticed the adapter cosplaying as a heating plate while charging the Mac.
There was an engineer who showed how shoddy many phone chargers are and how dangerous they could be.
That's also true of a million other categories of dangerous equipment, and yet almost none of them lock out competitors by using proprietary interfaces. A shoddy saw blade could kill me, too, but I still can go buy any blade from any manufacturer and put it in any table saw, and it'll work.
OTOH, there are gratuitous incompatibilities galore as soon as you get into software. Network protocols, file formats, executable formats, and so on.
What could explain the situations where we see compatibility versus incompatibility? If it's obvious and visible, and Average Joe can make it fit (like with a hammer), they go ahead and make it compatible. If it's secret and internal and they can hide the differences in ways that Average Joe can't work around (like software), they feel free to make it as incompatible as possible.
edit: Yes, of course some of the vendors will be gone or judgment proof. So don't buy from disreputable vendors. Which brings us back to the original problem -- if the user is willing to buy from them, they could just as easily be buying an entire laptop or a toaster for their kitchen. So solve it the way you solve those instead of stamping out competition, because you need to solve those anyway.
Or put it another way: If OEMs really wanted to solve this, they would stop overcharging so much for chargers and battery replacements so that people wouldn't have to play the Chinese equipment lottery to avoid paying a 1000% markup.
You may not get the chance. Some damage is irreversible and a lawsuit will probably only bring you some legal expenses. Preventing disasters is smarter and cheaper than inviting them and then clogging up a courtroom to complain that the perfectly preventable disaster actually happened after you invited it.
[0] http://www.righto.com/2014/05/a-look-inside-ipad-chargers-pr...
I recently bought a pair of Taotronics headphones from Amazon. They are a Chinese knockoff of more premium ANC noise cancelling headphones, at a quarter of the price.
The performance is incredible, and if you slapped a Bose brand on it, I could absolutely believe it's the real thing.
I would like to buy more "Taotronics-like" products from "reckless" marketplaces. For example, I'm looking at NASes. The top brand names like Synology are selling ~$40 worth of components BoM for $400. That's ridiculous!
Jeff Bezos is often quoted as 'Your margin is my opportunity'. As a consumer, I LOVE it.
Private sales are different than commercial sales.
I'd argue that any marketplace that allows other commercial sellers on its platform should be held accountable for anything safety and tax related their sellers do.
They should take necessary precautions to verify the sellers and routinely check the products. In Germany VAT dodging by Chinese companies selling on Amazon (let Amazon deliver with FBA and just don't pay taxes afterwards) got recently regulated so that Amazon is liable and the amount of Chinese crap dropped significantly.