I think public transportation is good in theory, but living in the Los Angeles area, I see many shortcomings.
What works:
The Los Angeles "Metro" system added some "Rapid" bus routes a few years ago. If you are lucky enough to live near one of the Rapid bus stops and travel on a week day, you can catch a bus running every 12 minutes or less, for the same price as a traditional bus. Most bus routes are every 30 to 60 minutes, which is inconvenient, especially if you have to go very far and transfer to another 30-60 minute interval bus. But at least Los Angeles now has SOME buses (and the trains) which travel at short enough intervals to be practical.
The trains, IF they are going where you want them to.
What doesn't work:
I've encountered this problem in Long Island, Washington DC, and in Los Angeles: You drive your car to the nearest park and ride lot, only to find there is NOT ONE single parking space left. You waste gas driving around and around the lot. You're stuck with either a) not being able to go to your destination at all, or b) having to drive there and hope you can find a parking space there.
Going from my house to downtown Los Angeles. A Torrance bus goes right by my house, and costs about half the Metro bus fare. It runs only once an hour, and stops just about every block before getting on the freeway. There are so many Metro bus lines running downtown via the freeway that I can't figure out from the map which one goes where I need it to go downtown. Furthermore, there's a surcharge for taking the express buses on the freeway, even with an all-day pass. To avoid the surcharge, I decided to take the trains. This involved taking the Rapid Bus to the Green Line to the Blue Line to the Red Line, about an hour and a half total, for a drive that would take about an hour in normal rush hour traffic. In my particular situation, if I had driven my car, my parking would have been paid for. It was a fun experiment, but would be a nuisance on an everyday basis.
Mom running errands with several kids in tow (doesn't matter if they're all her own, or some are day care kids).
People trying to economize on their food bills by using the strategy of grocery shopping just once a week. It would be very difficult to tote all those bags of groceries on a bus.
People running errands on Los Angeles buses during non-rush hours. It's too easy to miss a connection, even if you have figured out all the routes ahead of time. Then you have to wait 20-30 minutes or more. My last bus trip to a local mall was bad--the bus terminal was at the corner of the mall farthest from where anyone would want to go, and this is the mall that was the largest in the U.S.A. during the 1980s--a long walk, good for fitness but terrible if you're too weak to even drive a car! The transit company (Torrance Transit, which was referenced in the "Great American Streetcar Scandal" article linked at the beginning of this thread) has recently placed bus stops near the middle of the mall.
The Green Line to Los Angeles International Airport. Having two different transportation agencies involved, the much-needed rail line connecting the Green Line to the terminal area would need its own transportation board, because the two agencies can't work together. Maybe it's even ILLEGAL for them to work together! Mind you, a fit person could WALK this distance, maybe even dragging luggage--it's about 2 miles. Of course, no one has mentioned that the park and ride lot at Aviation Station is way too small. The latest story is that Metro is building a new line from downtown to the westside, and THAT could be extended to the airport, many years hence. It would be no good for those of us in the South Bay.
The financial side--does anyone know of any public transit system anywhere in the USA that actually turns a profit?
Finally, I would like to mention one more reason for the demise of the Pacific Electric system that I didn't see in previous posts: grade crossings. As more and more automobiles filled the streets, accidents at grade crossings became too frequent. Thus, modern light rail lines are usually grade-separated whenever feasible.