A quick thought, inchoate and probably none too original, but here it is.
I took the subway earlier today. I do that about once or twice a month when I'm out and about on the weekend and I don't feel like messing with traffic. I considered heading over to East LA for burrito at Al and Bea's but I decided against it because I didn't feel like waiting through multiple stops and changing trains. I never even considered a destination that would entail getting transferring to a bus -- that's only worth the trouble when there's a large cost to driving and parking (traveling to the airport is the only example I can think of)
That's the real hassle of public transportation, not the business of actually getting people from A to B, but the waiting, the loading, the unloading, the transferring and repeating the process. And that's just for a simple there-and-back trip. If you have multiple stops what would be a couple of hours of errands by car can take a day.
I got to thinking about the analogy between that and shipping before the advent of intermodal freight containers. Back then much of the time and most of the cost of shipping came from transferring items from ships to trucks then from trucks to trains then from trains to trucks. It was the innovation of putting all those items in a big, reusable metal box that made the modern age of cheap trade possible.
It struck me that we're still waiting for an analogous innovation (or set of innovations) in transportation, not just in buses and light rail but in trains and even air travel (what percentage of your last trip was actually spent moving from A to B?). Why we haven't seen more progress is question for another post (trying to avoid hydra blogging here).