There are different schools of thought on teaching reading and writing. So it could be someting to do with their particular philosophy.
To me a spelling mistake must be pointed out, and they must practice spelling it the standard way. I wouldn't labour it to the point of it detracting from the pleasure of reading or writing though, or in a manner that humiliates a child.
This suprises me though I thought the Swiss were hot on spelling tests. I believe in spelling tests, there are lots of ways to test.

With mathematics it is more clear cut.