Hmmm, mostly god yes, they are for people who need the extra space to get in and out of the car. That means people with disabilities and people with young children.
However, I did once park there before I had DD because the P&C spaces were under a cover and I'd just had a very expensive hairdo. It was pouring with rain, it was almost 10pm, and ALL the spaces were empty. So about 10 disabled spots and about 15 P&C spots. Plus lots of ordinary spaces that were much nearer the door - I deliberately used the one that was furthest from the doors. I was 2 minutes, just buying a bottle of wine (I was going over to the bf's house).
When I came back, all the spaces were still empty, but a man with a massive 4x4 was blocking me. I waited patiently for a bit, then I flashed, then I beeped. Nothing. Eventually I braved the rain and went over to him. He put down the window, and I asked if he could move. He said:
"Oh, sure. As soon as that small child I'm sure you're waiting for comes out of the supermarket."
I mean, what an absolute twat!!! His own kids, who looked like teenagers, were writhing in the back. I was cross by this time, as there really were lots of empty spaces. I pointed them out and explained that I would never normally use them, but I needed one that was under cover. He turned off his engine and folded his arms.
So I shouted that embarrassing your kids and dragging them to the supermarket at 10pm was probably worse, and went to get a security guard. Who told him not to be a twat and made him move.
Soooooo: mostly leave them for the people who need them, but there are SOME occasions when the parent is the bigger twat!