I'm also British. The American system is insane and catastrophically unfair, which is why you keep seeing news stories about how horrible it is.
The British "non dom" system is unique to the UK and is not any particular feature of residency based taxation (which is how every country in the world works save America and Eritrea). And there are constant rumblings about abolishing it or reforming it. I suspect non-dom status will eventually go away, but residency based taxation will stay.
At any rate, no country other than America has any chance of implementing such a policy. To make FATCA work required one of the most draconian laws that's ever come out of a democracy. Most people don't understand it at all. The law says that every financial institution in the world must obey the USA. This is enforced by not only taxing US assets, but because many institutions don't have any US assets, forcing those that do to recursively apply penalties to all their trading partners who aren't in compliance. A big part of the cost of FATCA isn't even reporting Americans to the IRS. It's keeping track of every firm you trade with and whether THEY are reporting their customers to the IRS ...... and then violating your contracts with them by withholding payments until they fall into line.
I see a lot of people saying things like, well, the threshold is high enough that all I have to do is paperwork. Or "it doesn't seem so bad really". I find this to be naive. Here's what can easily happen next:
• The threshold is lowered. As expats have no meaningful representation or organisation as a group, taxing them is effectively free money.
• The FATCA recursive enforcement infrastructure is extended to mandate global compliance with other US laws, by making banks impose penalties on any company or person that Congress doesn't like. People get upset as they suddenly realise that US law now takes precedence over their local laws.
FATCA is literally a totalitarian takeover of the entire global financial system by America. They don't care if people have to violate local laws in order to obey. The view of Congress is that American law supercedes all local law. It's the formal establishment of a global American empire.