Ok Rezdy: I happen to know someone who DAVKA walks in unexpectedly when someone is babysitting. She wants to make sure the babysitter is taking care of her child/ren properly and behaving as a bas yisroel should!!! SHE HAS EVERY RIGHT TO DO SO!!! If it bothers you when they walk in early, does this mean you have something to hide? I hope not.
As far as calling if they’re going to be late, that I agree. They should also leave a number where you can reach them if necessary. I also agree that there should be some snack and drink available.
There has to be mutual respect and admiration. There are rules for both sides.