I guarantee you they pay what the IRS code says for them to pay.
And not all wealthy people have significant unearned income. Most do, I'll freely concede.
But suppose you're talking about the interest they earn on their money. This is money that is coming from what was presumably their one-time income and has already been taxed.
If you tax it too much you reduce the incentive to invest it, when you factor in the risk, the inability to offset capital loss from capital gains, and tbe fact that the money has already been taxed when it was earned, what exactly do you think their fare share is?