Korean girls, or girls who live in Korea, is safety shorts really part of the fashion when wearing skirts/dresses?

I've heard that girls in Korean not only wearing safety shorts under their skirts/dresses, it's now part of the fashion.

You can buy many different kind of nice looking shorts that only designed to be worn under skirts/dresses.

Winter is okay, they snow in the winter. But how about hot summer? How to deal with high heat if girls gotta wear another layer of shorts?
Korean girls, or girls who live in Korea, is safety shorts really part of the fashion when wearing skirts/dresses?
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