waterless ones are patented and without a water line you'd be locked in to higher priced products and/or have to spend a lot of extra money to run a new water line after the walls go up. Generally the situation with waterless ones is people endlessly social signal their green superiority about them, then the incredible stench makes them install real urinals. Even if only 5% or so install real urinals the net cost is still lower.

Its kind of like an electrician demanding a ground line be run to every outlet while someone who knows nothing about electricity demanding that ground wire almost never carries current therefore is a waste of money.

Perhaps a better analogy is its like adding another fiber optic strand, before or during the project the marginal cost is extremely cheap, after the project is complete its unimaginably expensive to add another strand after the dirt has gone back in the ditch.