After reading that I think maybe a reward system would work better than a penalty?

Might encourage people w/ jobs who can't get to the polls to go and vote, but doesn't put unnecessary drain on their life.

They also should make voting day a national holiday, and give a tax deduction to companies who allow their employees to take as much time as they need to vote (given some lines can be hours long in places).

Edit: My comment is directed to the U.S.A. as that's where I'm from.