Actually the UK's Higher Tax Rate is 40% for income above £50k, but when you add in National Insurance tax the total rate of tax is 42% (with 28% for earnings between £12k and £50k).
For incomes over £125k under the Additional Tax Rate it's 45% (47% with National Insurance. So a significant number of high income workers do get taxed 45% or above, at least for a portion of their salaried/wage income.
The kicker is that the wealthy don't earn most of their money working for an income, they do it through investments, which is covered under capital gains tax. Income tax starts at 20% and goes up with income, meanwhile capital gains tax starts at 20% and goes down through loopholes.
The issue isn't income tax, that's just making the plebs fight against one another. The issue is capital gains tax and all the loopholes the ultra wealthy use to avoid paying their share. These people don't contribute to society, they don't work, they just make money off of their money and other peoples' work.
When Reagan was in office I think it was 95% for income over $1,000,000. He claimed that if he was getting taxed 95% for making a movie, he wouldn't make a movie, and everyone else involved would be out of work. Because sure, they're not going to just hire another actor instead... Unfortunately idiots believed him.