I think the distinction you make is important. Until fairly recently, not carrying ID was a British thing. Even if you still had it. It used to be an anti-totalitarian point of pride to not be required to present ID on demand. In Germany, carrying a form of identification is a legal requirement from age 16. Of course, anyone who drives in the UK still has a form of picture ID and increasing ease of travel makes passports more common. When mainland Europe is so close, why not holiday there? Whereas the US is so vast and varied that you needn’t pass border control. But this perceived freedom has been shifting in terms of everyday experience.

I don’t think anyone younger than 30 has ever not been carded at Tesco to do their grocery shopping, unless they’ve never had a drop of alcohol or needed an aspirin. I’ve been carded for buying a barbecue brush at Wilko (RIP). You see signs in shops that say that you can expect to be carded if you’re younger than 25. The point is, what was once seen as the government infringing on your rights in a totalitarian way is now expected from supermarkets. So you carry ID. And it’s not just at the shops. What X is doing isn’t anything Twitter wasn’t already. You couldn’t get an account on the birdsite without providing a telephone nr. In the UK, you get a SIM card contract by providing ID. Yes, people can get around that, but it’s so complicated that I would be surprised if that many have.

Clearly Twitter means enough to people for them to be willing to sign over so much, even when decent alternatives exist. I still think it has a lot to do with content, user numbers and wanting to be on the most popular stream. But it might also be that our perception of privacy is changing, as it has before.