I can't say Bill is wrong, nor can I say he's right.
But I can say that he has enough money to pay, nay, give to an independent non-profit that could be created just to solve this problem: how to get some of that ultra-rich money back where it belongs.
And taxation should be taken out of the things politicians can change.
Nobody is worth 1000-1000000 times more than a primary school teacher so nobody should have such income/wealth.
I don't know how it should be fixed but maybe some smart people would find a way.
Whether it's income or any other form of tax, it should be unavoidable.
Regarding the fact that "that their proposals would lead to wealthy people hiding income and stashing it offshore" I can say this: maybe they will, but if we can make them feel ashamed about it some may prefer to pay higher taxes.
After all, what are riches if you can't show your face around?
Let them show off on their private islands, but NOT HERE!