On paper, that's wonderful idea, but human nature works against it - and the wealthier the human is (such as many Tesla owners), the less important the potential incentive. People become very attached to things which they bond to their ego and are reluctant to lend them out unless the need for money is strong enough to make them compromise.

I agree, but I don't think that will be an obstacle at all - because I think there will be plenty of owners who just shift the mental "basket" they put their Model Y's into. These cars won't continue to be the cars that are their car. They'll be their side hustle business car. It's the thing that earns them money, that puts them on the bleeding edge of technology, etc.

They'll have a different car that's their car - perhaps another Tesla, perhaps paid for with the money they earn from their "working girl" Model Y. That different car is the one they'll bond to their ego, the one that's theirs alone that they won't lend out. They're not sharing that car. The robotaxi car is their business car, their former car, the one they still own but don't use themselves.

I suspect the bigger obstacle would be cleaning and maintenance, which higher-income car owners won't want to regularly engage in. But at the beginning, when the model is just soaking up excess unused capacity, Tesla may be able to economically provide that as an "end of day" service.