Why do parents let their kids wear shorts to school when it's under 40 degrees Fahrenheit outside?

I was subbing today. There was snow on the ground, temperatures hovering around 34, and there were kids wearing shorts to school.

I know that some of these kids ride the bus, and since we had a late start some of them could have worn shorts without the parents knowing. But way too many of these kids were getting out of a car driven by an adult that I’m assuming is a parent.

I get the idea of letting kids make their own mistakes. But isn’t this a bit much?