I think the op is right. They should be shorter. We are addicted to going abroad when it’s now 40 degrees and it’s making some places far too hot for having a pleasant holiday. I’d definitely take 2 weeks off summer and put it on to the Christmas and Easter holidays. Or 2 weeks for October and May half terms. The only issue is very hot classrooms in, say, August.
It’s true some dc dont retain learning and Scotland schools are back. We don’t have to be the same as other countries - we could move 2 weeks and we might enjoy 2 weeks at other times.