It is NOT the norm for people to do serious research about what it takes to take care of a pet. At least in my experience. This is exacerbated by commercial sale of pets, which imho is therefore much worse for promoting responsible pet ownership than renting. I imagine the Humane Society wouldn't have to put out as many "don't buy baby pets as presents" pamphlets otherwise.

A large percentage of pet owners also don't take their pets to the vet at all. At least renters'd have some experience having to feed, water, and walk the animals. More than what a lot of people experience. And while they might not know how to train the animals either, if they adopt the same pet they rented, it would theoretically not be as much of an issue - they'd be getting a pre-trained pet.