The problem is that sometimes there's a fine line to walk. Do you fail kids all the time and discourage them enough to make them drop out of school, or do you pass them up through the grades and hope something sinks in, despite them not knowing it all? I don't like either choice, but I'd lean towards the latter. It sounds like the case you're talking about is a bit extreme in the passing area.
I think in cases like the ones you mention (instances when you "don't punish the students"), it truly is daycare - keeping the troubled kids off the street.
As for that suing example, I think we can all agree that that is messed up, but I don't think that's common. I went to what a lot of people considered an "affluent" high school, and we never had anything near that stupid done by the parents. Although, we did have parents of kids in band who thought their child should have been principle chair simply because they were their child. Some people are just whiny brats, I suppose