"if you don't like them, go somewhere else"
I do agree with what you say, however not in the instance of schools. Does a kid go and look around which school they would like to attend like university students do? No.. Do they legally HAVE to go? Yes..
I think catholic (and all religious schools) are wrong, especially if they're public schools in areas with a large catchment area or a dense neighbourhood (in the sense there are a lot of people) as it's wrong to "force" or imply religion on the youths.