Well I think you might kind of be making my point-- not because I agree with you: I don't, I think man's ongoing impact on the atmosphere and climate is an important issue. And collectivist humanity is smart enough and wealthy enough to spare some resources on protecting our own future. But it's not an issue we're going to move the needle on with any amount of mandatory no-flow showerheads.

Intrusive regulation makes environmental concerns into people's enemy.

Because stuff costs money everyone already has an incentive to conserve. We can enhance that though lower impact methods like disclosure, monitoring, optional eco modes that can easily be disabled.

I suspect that considering the long term impact if there is virtually any public backlash these efforts are ultimately net negative.