Good grief. You have no idea of what you are talking about.
I have lived near this area for 40 years and know it very well.
It has no similarity to your “history”.
They are successful because there are several places you can find water in that area.
Later (Age of Zorro) the Mexican Revolution happens and California is relinquished by Spain to Mexico.
Development of California, particularly in the LA area continues ~ all the water resources are discovered and used for local agricultural development.
1848 shows up and California is absorbed by the United States.
Are you questioning the standard history of California taught in state schools just because you've been there 40 years and didn't see it happen, or, you are addressing some issue you've raised in your mind that wasn't raised in the thread?