I could rent every single one of these, but don't because the economics don't make sense, and the use model would otherwise lead to a lot of inconvenience.
Except it didn't work for ZipCar or the rental agencies that have added hourly options -- sure it's not bad, but is it really pushing people out of car ownership? No...
Ride sharing similarly hasn't worked to push people out of car ownership either -- it's just killed traditional taxi services by compensating drivers less and eliminating the flag down monopoly some cities have maintained (a taxi medallion in Boston/NYC used to be worth hundreds of thousands... no one wants them now)
All these share options work for low use scenarios like the city dweller who wants a weekly trip to a shopping center, but for the daily commuter/driver it won't ever make sense... and it'll never make sense for those that need to keep things in their car like child seats, diapers, a walker, tools, etc...
Bike/Scooter shares haven't eliminated personal ownership either because of the scarcity issue at peak times.
Have these people never been in the back of a taxi, or any kind of public transit?
In the early days, it was great. But once membership increased, there was an increasing chance that I would get a car that was not particularly usable.
Filthy on the outside (dirt, mud, etc) and/or inside (dog hair, bodily fluids, etc).
Or a car that had one or more warning lights illuminated (check engine, brake, no wiper fluid, low gas, etc).
And each time I had to phone into Zipcar support to report it (and/or swap cars), otherwise the next user could report it -- leading to me being charged some cleaning fee or such.
The best experience I had was in Seattle when I entered a dirty Zipcar and called support who said I had to take the vehicle to a car wash otherwise they would charge me a cleaning fee.
While I understand I could have probably escalated to someone who understood the situation ("oh? you just got into the car 5 minutes ago?"), I decided it was a better use of my time to avoid short-term car rental programs altogether.
Less hassle with verifying who actually trashed it, but also if you have to stare someone in the face after your ride, you'll probably be more respectful of the car.
But really, there's just not a satisfactory solution I can think of to make me want to use the service.
A couple I know in SF don't have a car but they seem to make a lot of use of cars in some form or other pretty regularly.