The difference is that the car isn't fully consumed but can be reused. So the lessor has an incentive of maintaining quality of the original good. This is the same for apartments (AirBnB). In contrast, food get's wholly consumed. How does the original owner incentivized to maintain quality?

If anything, you should spin this off to create a marketplace for food bartering system.

This is an incisive and articulate explanation of my reasoning. Ride-sharing and food-sharing are different in a few meaningful ways that raise doubt that a food-sharing app should be premised on this analogy. Not only is it the case that the lessor (donator) has basically no incentive to maintain the quality of the food, but the lessee (recipient) may have no real way to evaluate the quality, other than to trust the lessor. It may be obvious when the food has spots of mold or smells expired, but it's not always that easy to tell.

Luca, I don't mean to criticize your idea, which is a great attempt at solving the problem of wasted food. I just doubt that this model will really take off. I think you underestimate how squeamish people are about perishable food--even when it's their own food. I think people readily throw out food based on even a small chance that it is expired or smells "off." People don't want to get sick, and they especially don't want to make their families and friends sick. I think most people consider the risk of food-bourne illness (and the general ickiness factor of expired food) to outweigh the cost associated with wasted food.

I second the bartering system suggested above, which could improve the quality of the traded food. I think there's more of a market for an app that helps them keep track of when their food will expire, and to evaluate whether their food is safe to eat.

Anyway, congrats on launching your app, and I wish you the best of luck!