None of what I list is done because the sole reason of availability.

Googling wasted water brings up so much about households wasting water.

nothing credible? Any links to a credible source arguing we don't waste a lot?

There's a different between inefficient usage and willfully squandering resources like implied.

Water is a scarce resource with alternative uses. Most uses are of differing urgency and within each specific use, urgency decreases as the amount used increases. For example, the most urgent personal use for water is to drink it when you're thirsty. If you were stranded in a desert with a limited amount of water, you would drink it more slowly than if you had twice as much. Your need to water your lawn is far less urgent than your body's need for hydration. In a dire shortage, you would surely let your lawn suffer if your survival depended on it. Similarly, there is water price point at which you would forgo watering your lawn. It may be an absurdly high price, but it surely exists in theory.

In a hypothetical world with infinite water and no infrastructure cost, you would use use exactly the amount that would fulfill your desires. No other amount would make sense. If you could improve your happiness by 0.01% by using a million additional liters of water, you should. The real world with finite water but no prices should work exactly the same. The only difference is that you might have a moral imperative to conserve despite the lack of economic incentives.

Cool story, bro.

But people who aren't thirsty aren't going to start suddenly drinking more water because it has zero cost. Same with watering lawns. People won't water their lawns for hours at a time more.

Alternately, you'll still buy some water even if it was $100 a liter. It's something you have to have to live and there's absolutely no substitute for it. You'd be hard pressed to find something with a less elastic demand.

Leaving a tap on is the very definition of squandering a recourse.

There is a direct correlation between how likely people are to forget to turn a tap off and the price of water.

Also its highly arguable that spraying water over mud with some plants on top is a wastefull/indulgent/squandering activity that has simply become normalized.

Where water is scarce you dont see many lawns.

Going to spend the day breathing extra hard.

Uh, nice try there. Plenty of lawns in towns built in the desert out west.

So those lawns where there before massive investment in infrastructure to overcome water scarcity?

I live in ******g England, its wet. We still have hose pipe bans from time to time.

Think of the difference in what someone will eat at an all you can eat buffet vs. a place that charges per item. Are you saying they would eat the same amount? Have you ever seen the piles of food that are thrown away at an all you can eat buffet because people pile it on their plates and then don't eat it? People certainly squander something they see as paid for or free.