Youth games are paid onsite with a check though a couple weeks ago our crew got paid with envelopes full of cash at halftime of the last game. That looked just a little suspicious!
High school level games are paid through the association at our meetings. They collect our fees, and then distribute them to the officials so we don't have to work with the schools directly.
OAB, I've noticed that during most of my subvarsity games, we split right after the game is over. I enjoy getting together for a meal or at least a beer or two afterwards and discuss the game but most would rather just leave. Ah well.