The modern canal that runs through Phoenix is built on top of ruins of a much older canal built by indigenous people for farming.
It both is and isn't. Have you seen PETA footage from inside factory farms? It's hellish in that special way only the industrial revolution could produce.
Agriculture is largely practiced with industrial methods now, but it's been around a lot longer before proto-industrial methods (water and wind mills). For example, Egypt, as a civilization, benefited from the natural flooding and silt of the Nile. It's been the bread basket for empires for several thousand years. They were not using industrial methods two or three thousand years ago.
There are also other forms of agriculture that is not easily recognized by the narrow lens we have today -- such as perennial food forests, hidden in the ruins of Amazonian jungles, or the Pacific Northwest, or the forest that used to cover the lands between the Appalachia and the Mississippi river. Those were not organized with the concept of employment, and it is distinctively low-tech.
TLDR: America has spent a whole lot of money trying to make land more productive for farming, including land where it probably doesn't make much economic sense once you account for the infrastructure costs.
That canal became the basis for Phoenix, and eventually, the big canal that transport water long range through the state.
The other is that, with sufficient water, you can grow year round.
Not that I think industrial ag is good for society.
Phoenix itself is a metro area whose primary economic driver is real estate speculation. Many older citrus orchards has been surrounded, and sometimes bought and redeveloped.
California is a desert too.