The frustrating part is that it is possible. I quite enjoyed Calgary's bus system when I lived there. One bus every ten to fifteen minutes. Clean, modern, frequent, no crazies. My bus line was almost never exactly on time, but that is entirely because it had a turnaround time of something like six goddamn hours through cold suburban hell. It's probably because it's well-funded with oil money. Fundamentally, you need a city structure that benefits bundling rides to similar destinations, and with the absurdly polycentric nature of LA that's never going to be possible.
A friend visited Seattle lately. She was astonished when I told her Washington has no state income tax. "Why are your roads so much better? Surely your sales tax is higher?" No, lower. "How are you able to do it then? Vastly less graft and corruption. Unfortunately, graft and corruption are one of the principle aspects of mass transit in the United States. Seattle spent $125m expanding the monorail without breaking ground on anything.