Zaps can't be counted reliably by anyone but the receiver. So that means, lots of use cases like trending, paying for stuff or voting, not really gonna work. Maybe a future bolt or zap spec could improve on this, I'm not sure. I'm also not sure we would even want that if it did. One thing a vote could do, at least, is the person who posted the vote, could tally the results based on the zaps that actually arrived in their wallet after the vote is closed.