[tinotopia]

> Would you apply the same logic to oxygen instead of water?

Markets are a means of managing scarcity. Oxygen is not scarce, at least not if you're at sea level and you don't mind it mixed about 5:1 with nitrogen and a bunch of other gases.

For use in places where oxygen is scarce — like on top of a tall mountain or in an unpressurized aircraft at high altitude — you'll find that the stuff is very commonly bought and sold.