Well, let’s see. The UK wants mandatory ID because today you can walk in to an hospital and get $100,000 of free healthcare without even proving you are entitled to it. And you can maybe work without paying taxes. And you move freely and safely anywhere in the country.
In the US, if you do not have proof of citizenship on you at all times (and maybe even if you do), you may be snatched off the street, detained, and perhaps even sent to a foreign prison all without due process of any kind.
Wow, now that I say it out loud, you are right. The UK sounds like a hell-hole.