The top personal tax rate is lower than 40% and you only pay it on the
part of your income above a certain threshold, so no-one is paying
40%.

This is incorrect. Our top personal tax rate is 47% you pay that on anything
over approx $50K. I for one definitely pay more than 40% of my total income
in personal income tax. The same would go for any other professional unless
they are cooking the books.