So presumably AT&T did the next best thing for both you and themselves by silently(?) upgrading your plan to whatever was the new minimum of the new hardware while keeping true to the price lock to keep you as a customer.

There are ugly ways to cheat the system by replacing your stomach with a food sack and not chewing.

I don't want more data, I just want flexibility.

(If we really want to force a buffet analogy, it's like living in a dorm with a permanent buffet, but you're not allowed to bring buffet food into the lounge or back to your room.)

You paid for X amount of data, why does it matter if you are using it for a work VPN or browsing HN?

For the provider, the point of this design is that there's only a certain amount that people are willing to download on a phone or eat in a dining hall. For the consumer, they don't have to count their data or their servings as long as they follow a simple rule - they get predictable billing.

You see how that's bad, right?

My phone service, a utility, should not be micromanaging me.

We have a number of mobile services in the UK who explicitly offer routers with WiFi slots for replacing your home broadband with unlimited SIMs. I have used them in the past to replace the wired internet when there has been line maintenance that took out the broadband for a couple of days.

4G alone can get you a nice stable 100Mb/s.

You seem to be defending a shitty deal that happening in North America, without any clear reason.

My 60Gb can be consumed by YouTube, HN or tethering. It doesn't really matter to them.

Is this common in other countries?

I don't see any of the providers here in the UK with different amounts for tethering Vs data.