I think it is more than convenience. The real question is, how do we make public transportation less like a public service, and more like a profit-driven business? Call me a classest, but I don't want to have to share my commute with a schizophrenic who thinks the floor is a public bathroom, or with someone that's about to make Youtube's "best of fistfights on transit".
I've seen and experienced my fair share of sketchiness on public transit, but I think it's something important enough that I cannot imagine supporting a tiered transit system.
I can afford to drive - I choose to use public transit for lifestyle reasons (and the big bundle of cash it saves me sure isn't burning a hole in my pocket) and to support what I think is one of the great remaining equalizers in our society. I will gladly and willingly pay higher fares than poor people if it means increased accessibility for them to a system that, in all honesty, they need more than I do. When I walk into work 20 minutes late because the bus broke down, nobody yells at me - for people in less fortunate positions in life, it can mean getting fired. An effective transit system that is affordable, accessible, and reliable is an absolute requirement if you want to even begin fixing the poverty problem.
And none of this can possibly occur if we create multi-tiered transit. All you will get is super-effective transit that only connects wealthy areas, and a barely functional lower tier that subsists on government handouts, and can't even get poor people to work on time. It will simply become a gaping money-hole that serves no one - it will make taxes higher for you, and make transit much less effective for the poor, and worsen the poverty situation in your city.
Transit is one of those issues that is close to my heart, and one where I'm willing to tolerate a lot of imperfections, because IMHO it's bigger and more important than me, or you, or wealthy people in general.
Hell, even just as a simple reality check public transit has benefited me greatly - I find that tech people are paid well, and many seem to lose touch with reality "on the ground" after a while - I've heard some truly idiotic and insensitive words uttered by my coworkers about the homeless, for example. My nightmare is becoming yet another pretentious, arrogant upper-middle class suburbanite tech worker, and I think riding transit daily at least does something to keep that in check. At least it won't let me dehumanize people poorer than I am like so many wealthy people seem to do.
We'll spend an incredible amount of money on health care and social services, but they will never be terribly effective. I've never seen a social service that was effective at anything but spending money. However a profit-driven business could make headway towards solving many transportation issues en masse.
