I think P&C spaces are useful and a good thing. Yes, we did without them, in years gone by, but in days gone by, we also did without car seats, rear seat belts etc, and cars were smaller - you only have to look at a vintage mini beside a 'new' one to see how cars have grown.
So P&C spaces are useful because they allow the car doors to be opened widely enough for a car seat to be manoeuvred in, without the risk of banging the door into the car next to it.
It also makes it easier to get older children in and out, and strapped in, without risking damage to neighbouring cars.
Yes, these are not necessities - they merely make life easier - but that does not make them the brainchild of Satan. Dishwashers make life easier, so do supermarket trolleys with child seats or places to secure a baby car seat - are the P&C space haters going to give up the things that make their lives easier? No? Didn't think so.
All that said, P&C spaces don't need to be right next to the shop. Put them further away, or round the side of the store. It would be helpful if there were a walkway to the shop, but that's not a necessity.
I do feel, sometimes, there is a dog-in-the-manger feel to threads like,these - a sense of 'Why should someone else have even the tiniest benefit that I don't have? If I can't have it, I don't want anyone else to have it, even if it makes a busy, tired parent a bit more tired.' Doesn't it sound a bit mean and petty, put like that?