I think they mean using it as an excuse to politely decline going to things you don't want to go to.
"Oh, you know I'd love to help your aunt Carol move her collection of antique furniture to her new fifth floor apartment in the August heat, but oooooh dang wouldn't you know it, I don't have a car to get there. Drat, sorry about that! Maybe another time, for sure!"
I'm not in a place with Uber and I'm trying to avoid being compelled to go anywhere. Anyone that expects me to sweat to visit them is smoking crack. That's why not having a car is great. Nobody can expect me to be anywhere I'm in control