I have to say for the babysitter situation is actually pretty normal. The way to look at it, is how much is the person making vs paying for a babysitter. I babysit and I get paid 15 a day and if its a long day then its 20. There is no possible way for someone to be paid by the hour, unless you are rich.
There are people here that charge $5/hr per child. That would mean I would have to dish out $15/hr for a babysitter when I only make $14. That person also doesn't babysit much.
Now babysitting and being a nanny are 2 different things. Babysitting just means taking care of the kids. Making sure they are fed, but doesn't mean they make the food. They do not clean, cook, bathe the kids etc.
A nanny will do much more. Which they get paid more because of.
Children are expensive little creatures.