If you wanted to rent your car out like this, how hard is it to set up an LLC so if god forbid something like this happens, they can't come after you personally?
Simply setting up LLC (or any other type of entity) is not sufficient. To shield your personal assets LLC needs to be properly capitalized and be managed like a proper business. Essentially, it will at least require carrying some kind of commercial insurance, plus having extra money in the bank for operating expenses (how much - depends on the business).
This sort of defeats the idea of effortless car sharing.