It's already possible to self organize car sharing, with a spiffy app, insurance rating systems and . But keeping the car in good shape and checking it, as well as the risk on non-availability (which might get better with a self-driving car, but no one wants to wait for the car to driver 30 minutes back) now make it an unattractive option compared to commercial car sharing.

At least here in the Region of Stuttgart, Germany b) and c) mostly don't apply (and I'm pretty certain they don't in most other parts of europe) and most issues with public transit here (limited core capacity leading to overcrowding, higher prices) similarly apply to cars and automated cars (with congestion and usually higher cost of ownership than public transit time cards) and can't be solved there either by an individual. The unique issues not common to other modes of transport are bad service in some parts, depending on the route a long duration compared to car travel and an aging infrastructure leading to a few issues (but due to be replaced in the near future™).

Most of those stem partially from chronic underinvestment with some rail connections closed in the 50s still not being reactivated. But unless a car isn't needed for the daily commute (due to public transit or more home office or active transportation) it's hard to imagine car sharing or self driving cars helping a lot.