There's a reason LA has shorter commutes: because highways and car traffic don't scale, and subways do, so it's impossible to get as far as you could with a subway. Los Angelenos still have 45 minute commutes, they just don't get as far and burn a lot of petroleum getting there.
The average commute in NYC is 45mins, which is almost 50% higher than the national average. LA always has a below average commute time.
The fact that LA metro has such short commutes - despite being one of the largest and most car dependent big cities in the world - suggests that highways and private cars do, in fact, scale very well.
While I've never been there, my impression of LA is that it's very sprawling. Maybe not everyone has to go to one central area to work. Unlike Chicago's Loop or lower Manhattan where a lot of the commutes tend to converge in one general area. If few people have the same commute destination, individual cars would be more effective than mass transit.
That problem is already solved, and it doesn't require light rail: Privately run shuttles and busses.
It'll never happen, as it's opposed by (1) Taxi operators, (2) Mass transit operators & unions, AND (3) Do-gooders who don't want private business to succeed where public service has failed.
