In regards to your first point, the system would have to be based on the offender's net worth rather than their income in the US, due to all of the tricks that the rich have paid to create in the tax code.
He was talking about hiding it. When things are hidden, tax loopholes are irrelevant because tax law isn't applied to the money in question anyway. If you can hide income then you can probably also hide the accumulated assets.
And as for loopholes, was the idea really based on income, or was it just taxable net?
Speeder: "Your honor, I have dependents and pay mortgage interest, so my fine should have exemptions and a deductible applied before you calculate my fine."
Speeder: "Furthermore, a lot of my income is from gains, so I should be fined at a lower rate than people who have jobs."
Judge: "Wow. You think I'm with the IRS."