It is possible to get a sleeping baby out of a car seat without waking them.
Haha ok I wouldn't take the risk if I didn't have to.
If someone has parked too close you pull the car on the space and park side on to it to get your dc in.
With the baby in your arms and the 3 yo standing beside the car 
Or, we could admit to the fact that we DO live in a first world country and have a few small spaces specifically to make those who struggles lives a little tiny bit easier.
There are about 3 at my local tesco fgs, your lucky if you would get 1 extra car in if they removed the extra space and shoved them all together.
They're a godsend when you have an infant carseat your taking in and out, or if you're on crutches, or not disbled enough for a blue badge.
I don't even drive and I really don't see the problem with them if they are for infants who can't walk and those with temporary mobility issues.
We should call them "accessible" spaces though in the hopes of putting of people who don't actually need them.