Why Is There A Curtain On Voting Booths?

Looks like a changing room, but nudity is discouraged

In my younger days I had a strange habit of masturbating in voting booths while repeatedly screaming the words "America" and "Democracy", but these days I've become rather disillusioned with the whole political process and I think I'm going to start shitting in the voting booth instead. That's probably the only REAL way to get your "voice" heard anymore. What's the difference between your average voting booth and a port-a-potty anyway? In a port-a-potty you take a huge steamy dump that drops into everyone else's collective shit and in a voting booth you drop your wishes for a better country on top of everyone else's. They're both a place for pointless cathartic activity and neither ever seem to have toilet paper in them. I always wondered why we don't get Election Day off from work, but you don't get the day off to excrete a bowel movement from your rectum either; it's something you're expected to take about an hour break for and come right back.