Even if you completely eliminated lawns, you wouldn’t make a meaningful dent in water consumption.
It's only in the past decade or so new development has started requiring drought tolerant landscaping. Municipalities have also recently introduced ordinances to limit watering. But this is all a reaction to the serious droughts we've had rather than being proactive.
Grass lawns are a waste of water, gas (mowing/maintenance), time, and effort. Reducing grass lawns in residential and commercial spaces would make for a meaningful reduction in the state's water usage with little reduction in economic output.
When that water evaporates, it goes up in the air, and then falls back down as water.
But water is not a scarce resource and putting it on plants is not a negative sum game.
The planet recycles water. Grass is 100% sustainable if maintained using the planets natural water cycles.
The water in the sky falls on a water shed which is harvested into a local water supply which comes right back to a tap.
Not everywhere irrigates their lawns.
But I agree with the sentiment. The amount of energy I see in the US being put into maintaining an artificial environment in places that otherwise would be barren is astounding.