As long as the money just circulates through and never falls into any person's hands, who cares? At some point some human being is going to want another mansion or yacht. When they reach their hand into the pot that's when you grab them and take the government's cut.
Nobody is going to waste their life shuffling funds around and endless loop of shell corporations with no intention or method of eventually extracting some of it.
Imagine a Kennedy or Romney getting a house foreclosed on because the local government requires property taxes to be paid in cash. Or unable to restock on champagne and caviar because the clerk at the checkout doesn't accept "I own umpteen offshore corporations" as a valid method of payment. Or cleaning their own pool because every pool boy wants cash, no numbered Swiss accounts please.
The folks running these tax scams aren't doing it for kicks. They're doing it because they want to live high on the hog. As long as the taxes on their luxury lifestyles are in fair proportion to the taxes on us regular folks and our regular lifestyles who cares how the corporate books are structured.
Incidentally all those offshore shell corporations are setup by lawyers and accountants who ultimately want a cash paycheck to buy stuff with. If the CEO can buy another yacht by laying off the hoard of lawyers/accountants that spend their days fabricating shell corps he/she certainly will.
BTW, I support taxing cap gains same as income. If you had X dollars yesterday and X+Y today you owe tax on Y. I don't care where it came from or how you got it. If you're a human being you owe your fair share tax on $Y.