In a dense area like Manhattan, transport is not so bad because walking, cabs, or the subway are all viable alternatives in many cases.
In a lower density sprawl area like Los Angeles, cabs are prohibitively expensive for most trips, the subway usually doesn't go anywhere near where you are or where you want to go, the buses are stuck in traffic like any other vehicle, and walking is dangerous (due to the lack of pedestrian-friendly sidewalks in many areas) and would take many hours for each trip.
I think the best way to fix LA traffic would be to greatly increase the density and start building upwards so that walking and public transport become viable options for many more cases, but that seems very unlikely to happen anytime soon. It'd take decades to do anyway. So for now, it looks like LA is just stuck with its insane traffic status quo.