I suspect it has something to do with LA's large footprint. Comparing to where I'm from in Chicago, LA county is over 4x the land area with less than 2x the population:

https://www.comparea.org/r122576+r396479

Don't know how the math works out exactly, but if they don't have the workforce to cover their patrol area with squad cars, there's probably an argument to be made for covering gaps with areal support. Given that Chicago struggles with workforce shortages, I can only imagine how much worse it'd be if you had to cover 4x the area with half the tax base.