I should have thought that any shorts are going to be cooler than long trousers just because there is so much more skin exposed and air able to circulate more easily.
From experience the fabric the boys short trousers are made of isn't very thick at all, hold them up to the light and you can practically see through it! Extremely poor quality in my opinion. I don't know many boys of school age who would want to wear gingham shorts either, far too babyish.
Just wondering why little boys can't wear gingham shorts, in the way little girls can wear gingham dresses. They'd be much cooler than the usual thick grey / black shorts boys get stuck with.