While I think this could work in NYC, Seattle, or San Francisco, most other American cities have plenty of infrastructure and affordable parking to support a high percentage of car ownership amongst citizens.
Heck, there was even a HN article a day or two ago about how parking spaces in America outnumber actual cars by a huge margin in most American cities and towns. I think in one city it was 80 to 1.
Unfortunately, the US is still too spread out for these types of services to be useful in all but a few cities.