I’m generally pretty left wing, but I think it might be sensible to point out that high earners wouldn’t have to “leave the country” if they felt they were over-taxed.
OP countered the beer-drinking analogy with a chat about how the poorest men were also pulling the pints and wiping the tables. I would assume - although I could of course be wrong and they could have a second job - that in this hypothetical world, they pulled pints for an 8 hour shift, and then went home and didn’t think about work again until they turned up for their shift the next morning. They might have seen friends, gone to the gym, watched TV or played football, and still had a full 8 hours of sleep. They weren’t laying awake at 3am worrying about whether they were pulling pints correctly. When they’re off, they’re off.
There are, I would say, a vanishingly small number of jobs earning £200k where you can do that. DH does this sort of high earning job and I used to. He usually works until 11pm as a minimum - if we are doing something in the evening, I need to book him several weeks in advance (so that he can work until 1am the night before…) He is often laying awake at night turning over a difficult work problem. I can’t remember the last time we watched TV. We have just come back from our summer holiday, where he worked for several hours every day - there was nobody else at his start up who could do the thing he was being asked to do. Our life has been like this for probably 25 years. DH grew up in modest circumstances (as did I) and he feels strongly that he wants our kids to have different opportunities. Many people would be horrified by the thought of living like this, and I’m sure that I’ll get a raft of reactions saying that he is a workaholic/ only cares about money etc. But that’s sort of the point - not everyone is willing to do this. I don’t think it’s true to say that high earners are earning “more than their fair share”, if they’re doing things that other people aren’t willing to do / living in a way that other people aren’t willing to live. They’re not somehow “cheating” or behaving badly. In some cases (not all, of course, but enough that we shouldn’t be making blanket statements), they just have a different picture of what happiness looks like from other people.
Would he carry on working like this for half the money? Probably not. What would be the point of missing that time with the kids if he didn’t have something else to improve their lives in exchange for the time (whatever your view on the rights and wrongs of that trade off)? If I were taking home the same amount as someone on £70k, I wouldn’t be willing to take on board either the hours or the stress of a £200k job - would you? He’d just do the £70k job and be calmer. Nobody needs to move abroad.
I should say that of course there are careers with that level of stress that command lower salaries - medicine is the obvious one. But even then, there’s a choice to be made for consultants between working for the NHS for a (relatively!) “normal” number of hours per week for perhaps £90k and then also doing private work during evenings and weekends and earning potentially tens of thousands more. We could tax them more but they might make different choices. Faced with two ways of taking home £X salary, where one involves twice as many hours and twice as much stress as the other, many people would choose the simpler route (and pay less tax).