I think the important factoid to add to this is that DC vehicle registrations are flat during a time of growing population and growing affluence. This (mostly) isn't about the recession or poor people not being able to afford cars, it's about people deciding they don't want to bother with one.
I imagine there's a pretty big peer group effect to all of this, a bit of a tipping point. It's easier for me to not have a car because most of my friends don't have cars. People don't propose plans based on the assumption that all involved have cars. There's no regular "need" for one.
Cars are useful things and much of the country is built around them, but even in urban hellholes policy has been focused on the car for too long. Hopefully this will catch up a bit to reality.
