How do mining pool operators work?
You, the miner, are the one being paid by the pool operator for doing some computation. It's a free and open market. You can switch pools if you're unhappy with the reward or the honesty of an operator.

To become a pool operator there's no election process or formal checking whatsoever. Again, it's a game based on reputation. Just like any other business, if an operator misbehaves (by stealing funds or something), they lose reputation and therefore users.