A car is a complex piece of machinery. You keep everything on your car running absolutely perfectly? Well, it's great if you can afford that. Probably you're not in the target demographic.
Most people who share their own rides assume it's at least going to break even, if not much more. But if there's an accident, how easy is it for the driver to just claim it was the car? They can ditch the fault if the car itself was faulty. There's just too much incentive for a stranger to take advantage and cost you a lot of money.
The premise of ride sharing is the willingness to put yourself at someone else's mercy. It's a basic foundation of trust between two non-familiar people that doesn't exist in our culture.
OK, so take the human component out of it. What's left is a for-profit corporation handing cars out for cheap. No one should be surprised when people take them up on the offer out of economic benefit! They are able to provide cars for cheap, if they are in your area, and you want a cheap char, why wouldn't you use them?
I think they should fully accept your fate, and pivot into the worlds absolute BEST rental car company. Just maximize utilization! They've built all the infrastructure they need, they could kill it in this space like UBER is killing it in valet.