What? Trust is the very bedrock of civilization. You trust people in little ways every second of everyday. You trust the mailman isn't reading your mail, you trust the coffee at the diner isn't contaminated, you trust the health inspector that inspected that diner, and so on.
All business is about establishing trust. But standard practice in business is never to expose yourself to undue risk. The business side of ride sharing just doesn't compute, because the benefits don't outweigh the risks of letting someone else drive your car in exchange for money.
Businesses carry insurance, and they operate under a completely different tort of liability. A well operated business will never risk sending employees to jail because a car they rented crashed. They may be fined, but you would need to prove willful negligence to get a criminal charge.
On the other hand, lending your car out as a individual exposes you to massive civil and potentially criminal liability. You don't have to literally booby-trap your car to be charged, you could be charged merely for a component failing at the wrong moment (hindsight is 20/20, and juries are people).
I don't think they are leaving it on the table, I think their schedule of fees means they are carving out a spot that the rental companies totally ignored.
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.