Yes, Public transportation in Los Angeles is dismal compared to other major city areas. I remember when I first used the BART and was astonished at the difference. Forget about trying to use pt after 1 am.
I agree, the concept of Los Angeles as a city proper really can't be used when discussing the region of Los Angeles, it's pointless. Just look at this map outlining the city limits of Los Angeles:
I can (and do) traverse across several municipalities on any given night out or trip to the beach.
But is this really peculiar to city of Los Angeles and the idea of Los Angeles? I don't think many tourists know that Beverly Hills isn't technically Los Angeles, and I don't think outside of a few overweening Beverly Hills residents many people would care.
Burbank is where most of the studios are at, but don't tell this to tourists.
Santa Monica isn't Los Angeles, but this is where many tourists come to go to a beach in Los Angeles.
Anyway, this region is a total wank because it's nothing but strip malls after strip malls with the occasional posh neighborhood breaking the monotony.