That's a poll tax, and in implementation is what is known as "regressive". That $50 is far, far more dear to some minimum wage single mom, than a CEO. That in fact is the objection to many of the voter IDs GOP states keep pressing for; the goal, as stated, is simply to prevent voting fraud, but the actually results are to disenfranchise the poor, who can't necessarily afford the $25-50 cost, nor can they afford the time off work to take public transit to a DMV (or similar) during the times they're open. Effectively, you're setting the bar higher for the poor than for the rich to vote.