Why? Subways are found in larger cities, airports are everywhere. Live and work in the countryside, travel to holiday destinations and you're done. Also, just because there happens to be a subway doesn't mean you need to use it. The times I've been to Washington DC I've managed to avoid using it entirely. The place is fairly compact and lends itself to walking to where you need to go.

Well, sure, if you don't take subways then you're not likely to be on a crowded one.