Should Japanese pupils wear shorts in winter?

In Japan, primary school students wear a lot of long-sleeved sweaters in winter, but only a pair of shorts. Note that in winter, you wear a sweater above and shorts below. This is a European custom, which Japan copied. I don't think it is good to wear shorts in winter. I think China's dress code was the best in the 1980s and early 1990s. At that time, there was no school uniform. More than 95% boys in primary school and junior high school wore shorts in summer, more than 90% wore sandals barefoot, and 85% boys in high school wore them like this. At that time, the only children of very rich families wore the same clothes, but no one wore shorts at all in winter.