Unfortunately I find that I'm far too uptight.
There is one mum at dd1's school who has a three year old daughter who insists on coming to pick up her brother from school in just her knickers. The mother is not bothered about it at all, "as long as she's wearing shoes"
Also, outside dd1's classroom today there was a massive puddle and three three year olds were jumping in and out getting soaking wet. I would probably get annoyed if dd2 did that...