Sorry to be the skunk at the garden party, but the Constitution 24th Amendment states that the right to vote "shall not be denied or abridged by the United States or any State by reason of failure to pay any poll tax or other tax." A fine would be a tax.

How about the opposite. A vote receipt redeemable at any US business, paid by the US government, for say $50. Dark money already dumps billions into presidential campaigns. A $10 billion rebate is a drop in the bucket of our multi-trillion-dollar annual budget. And besides, that $10 billion could only be spent here in the US of A, contributing to our economy.