Sea level Island locations get more wind drift and loopier trajectory due to the denser air. Thus a larger KZ is used more.
It is based upon what works locally, and what gives a degree of challenge that is a test of skill rather than a game of chance. A13mm KZ 4500ft up in South Africa is not as hard to get as a 25mm at sea level.....even when you factor in wind.
A universal set of KZ sizes won't work.