Water isn't scarce here and obsessing about not leaving the faucet on make little sense when you compare it to the water spent when flushing toilets and taking showers. If I lived in a place like Hong Kong I would be more careful about my wastage.
I don't obsess over it and like I know my caution is irrational and has nothing to do with actual scarcity. I just feel bad

I guess because I grew up being told not to waste it. My grandmother drove that shit into us and used to tell us about how she would spend all day climbing this big ass hill with buckets of water so that everyone in the family had enough water to bathe and drink and she could cook. So it just became habit.
I also tend to hold my piss in a little longer sometimes because I tend to do full pisses every 30-60 minutes (Ironically I drink a shitload of water) and every damn flush is 1.6 gallons or something.
Edit: My mother's family (The Mexican side) also used to go crazy about water because we lived in the middle of the desert and they were poor (and trashy) as shit. So you'd only flush with poop. Pee would have to stay until 3 piss sessions or someone pooped.
I lived with them for a year :'(