Going by recent threads, it is more likely that you would be cancelled as a customer and still have to pay for your reservation.
Like, round the corner from me right now is a VW Golf. I can jump in it and drive it away immediately for €0.30 a minute (pricing is demand-based, it can be cheaper than that). No additional costs whatsoever, the only condition is I have to park it somewhere within their operating area when I'm done with it.
If I want to keep it for a few hours, or a few days, all I have to do is choose the appropriate tariff. A certain amount of kilometres is included, and I can buy more if needs be. Doesn't cost me anything to park it in the city while I have it. Sure, it gets a bit pricey, but that's the cost of convenience.
Traditional rental is a bit more complicated, but not hugely - book through the app, collect, return. Anything longer-term than that is available through a monthly subscription, which is certainly more expensive than a conventional lease, but everything's taken care of and you can hand it back any time.
It's all pretty painless.
I'm in Germany, which may obviously differ from the US, but here's what I see: In cities new app-based services that are much, much more convenient to use take over. But they're only available in large cities (and even there only in the inner part of the cities).
If you need a car from "small city X" to "small city Y" there's simply no company other than Hertz, Europcar and Sixt that can offer you that. And it's hard for any other company to create such a network of locations.
Uber car rentals is just a proxy for traditional car rental services like Hertz. All the aforementioned problems like reservation flakiness and weird fees applies.
On the other hand, Lyft car rentals is operated in-house and feels delightful in comparison. I usually reserve a few days before, take a Lyft to the fleet HQ with the provided credit, and roll out in <10m. Overall a super nice experience both times I’ve used it.
Am I being an idealist? Are the dark patterns and hidden costs mandatory to become profitable? What are the unit economics preventing from such a thing to exist?
Renting car is painful and stressful if you're not a business user (or high tier member).
Yeah it seems it'll be pretty rough and capital intensive entering the market, but it seems so obvious that I wonder why there isn't a company like Uber or Airbnb that VCs want to pour money into. Turo would be the obvious comparison but I don't think the same model can apply for cars.