That's true, but it's much easier to pay for the 20% of a car that you actually use when you're renting it as needed.
While it's less obvious with housing the same applies: People buy houses that are bigger than they need at any given moment so that they have the space they need to entertain guests, or house prospective (or past) children, etc. It's much cheaper for me to put my parents up in a hotel when they come to town, than to keep a guest room idle for the next 20 years of my mortgage.
The utilization argument about rental cars is valid when and if we get driverless cars. Until then, the amount that you pay the driver completely destroys that savings.
(And in fact you pay for more wear on tires, gas/electricity, and other per-mile costs with rideshare, because the car travels more on your behalf than would a car you own.)
How much house you want/need is a valid concern, but not one that really cuts towards the question of renting or owning your primary residence. You can buy a house without a guest room. I did!
While it's less obvious with housing the same applies: People buy houses that are bigger than they need at any given moment so that they have the space they need to entertain guests, or house prospective (or past) children, etc. It's much cheaper for me to put my parents up in a hotel when they come to town, than to keep a guest room idle for the next 20 years of my mortgage.