But then I'd have to park it, and just that would double the monthly cost. And then I'd probably use it once a month on average.
A taxi service is an essential complement to mass transit, and Uber provides that service in areas with poor taxi service (essentially everywhere).
How much would it actually cost to commute 20-30 minutes to and from work in an Uber? $40 a day? More? Let's just say its 40 and you strictly commute during the week so that's $200 a week or 800 a month. Even with bad credit or no credit you would be able to save for a car rapidly. The $2000 car would only take 10 weeks to pay for fully in cash and the savings of 800$ per month could easily cover maintenance.
My point is if you can afford to use Uber as your sole means of transportation you can surely afford your own car and the people who can't are using subways or Buses. It's pretty simple, people who are struggling aren't using Uber very often.
Believe it or not, there are people out there who don't have $2000 and these people are also the same ones who can't get anyone to lend them money.