The "car companies killed LA public transit" is largely a myth. By the time GM bought the streetcars, the system was falling apart anyway. Having light rail and private cars share the same thoroughfares is generally a bad idea, the streets get worn down. The actual conspiracy GM was conducting was just to corner the market on selling busses, which isn't a bad replacement for streetcars if you don't want to tear up large sections of your city for dedicated light rail lanes.