It's much colder than that here right now, but I see plenty of idiots men walking around in shorts, including some postmen.
I was in a warehouse type agricultural retail shop recently, quite cold inside. I guess it was about 10 deg C but only as I would have expect such a place to be. Outside was several degrees of frost. I was wearing jeans, arran jersey, a thick anorak and boots, and I felt fine. But a guy came up behind me at the checkout looking like he had just walked off a summer beach - shorts, a thin brightly coloured T shirt, and sandals. He was slapping his arms around himself saying loudly "They ought to get some heat in here!".
It is this "Benidorm" culture, where guys like him expect to wear summer clothing all year round, in every room of the house and everywhere they go, which is a lot of the trouble. It seems to be fashionable, whereas I'm not. Woollenwear is something that many people would not want to be seen dead in. I hate to think what that guy's heating bill must be.