Air Force Uniforms

Why is the colour of flight suits (worn by pilots of most countries) green? I cannot imagine it being for the purposes of camouflage. Also in the desert, many opt for tan.

In the Cope India threads/pics, the Indian pilots are always wearing blue (only non-green, non-tan country I think), whats the history behind that?

Also the Indian technicians seem to wear the exact same flight suits as the pilots whereas in most Western countries, the maintenance personnel simply wear tees/BDUs. Why is that? Aren’t flight suits supposed to be more expensive than just tees and BDU trousers?