What happens when there is a mechanical failure during morning or afternoon rush hour? Things break.
I use a semi automated parking garage in NYC because my customer has an account with the garage. I walk in and the attendant is fiddling with the hydraulic lines on the car lift, and cursing how it’s in bad shape. I specifically tell the other attendant retrieving my car to put my car on their other lift to get it back to street level.
He puts it on the sketchy lift, and the hydraulic line snaps between floors. Safety break on lift stops a freefall descent (always heart stopping to watch your car falling at 20mph straight down in front of you). My car was stuck for 8 hours on a Tuesday evening. Freezing cold and I had left my jacket in the car. God damn nightmare getting home that day.
There are however new condos being built on the West Side that have private car elevators and parking spaces, on your floor, directly in front of your front door. Those are some cool condos. At about $3500/sf though. Supposedly being built by the heirs of the Monaco crown or something like that.