The only "de facto standard" in kitesurfing seems to be red on the left side, and whatever rocks your boat, or the manufacturer, on the right
So actually half a standard ha haa !
I would say though, that left red and right green is the only standard there could be, it there should be one
A friend of mine rigged his kites with "whatever side was present first", so often red was to the right.
Whenever I borrowed a kite from him, it was confusing when I spun the bar around multiple times - which side should I grab for ?
Or when popping up after getting rolled in a wave, and you want to avoid the kite getting "crunched" in the waves, you pull instinctly and fast on the bar awaiting left is red.
So I definitely see it as a safety issue, and very egoistic if you "dont care".
It could also be someone trying to help you if unconscious or in trouble, and wanting to keep the kite "stable" on the ground or water (if not possible/wise to release), thus you pull on one side of the bar awaiting that red is on the left