A thought: if it's true that ride-sharing and AirBnB use cars and living quarters more efficiently, thereby reducing the number of cars we need as well as the demand for land to build hotels (cet. par.), shouldn't that be a really good reason for environmentalists of all political persuasions to support them and oppose regulations that restrict their expansion?
There's a strong green case for the platform economy in electricity markets, so why not for the rest of the platform economy? Efficient use of scarce resources is both economically and ecologically commendable.