Our society, like many others in the capitalist West, tends to view consumption as an indicator of social standing. That new flat-screen, the latest iPhone, the granite countertops in your kitchen, they all indicate that you're winning the rat race-- and it's expected that, if you're winning the rat race, you're also engaging in this status-oriented consumption. For a society that is largely without formal class consciousness-- we're all the middle class, don'tcha know?-- we are all astoundingly sensitive to informal class distinctions. Grocery stores, shopping centers, neighborhoods, cities, these are all divided along the income strata. (Don't believe me? Walk into a Food4Less, then into a Ralph's. Then remember they're the same company.)
And, of course, one of the biggest categories of status consumption and differentiation is the car. Cars are heavily differentiated on status-- even those of us who don't drive are constantly indoctrinated into the relative worth and value of a BMW over a Honda, or even the petty distinctions between, say, the Mercedes C class and E class. Our society constructs cars as an outgrowth of their drivers' identities, and if you're willing to be seen driving around that 5-year-old Civic, you must be a loser. So, of course, if you're not driving anything at all, you must be at the very bottom of that capitalist totem pole.
This status differentiation means that, outside of the very densest cities-- and, often, even within them-- we design public transit to be sensitive to the needs of the poor. Worse, we design public transit to be sensitive to what middle-class, well-educated, mostly-driving public transit planners imagine the needs of the poor to be. This is part of why transit is only active during the day, because the poor need to get to their (wrongly assumed to be 9-5) jobs, but not to the nightlife they can't afford to partake in. It's the reason that buses don't serve all of the schools-- especially in wealthy neighborhoods-- but do serve all of the welfare offices, and make the Woodcrest office of the Social Security Administration into a transfer point.
The status and deference that people expect to accrue to them as drivers is also part of the reason that it's so hard to get what ought to be simple improvements in our cities-- such as market-priced parking, reduced parking minima in the zoning code, meager improvements in transit service, and road diets on overbuilt infrastructure (I'm looking at you, Brockton). Cap'n Transit, a phenomenally snarky New York transit blogger, talks about the fundamental unfairness that stems from recognizing drivers' choice to drive-- even in eminently transit-saturated New York City-- as a reflection of their social standing. The details of the plan he's critiquing-- congestion pricing in Manhattan-- are unique to New York City, but the dynamics of having to throw a bone to the driving classes when trying to improve transit are pretty universal.