“Since good jobs are almost everywhere in LA County, this requirement can likely be met ”
Not so much,
you’re starting an urban legend I think.
Especially for defense and high tech, they are spread out fairly well.
Entertainment is mostly in one general area however but even then you can easily find yourself driving sometimes 100’s of miles to get to the shoot.
Also a lot of times the High Tech company, started as as small company next to the Rich guy’s home who started it, you’er average worker engineer needs to drive unless he wants to live in a condo (mostly what he can afford there and these can run 500K-700K for a 2 bed 2 bath in some area’s in L.A.)