yes they get pinched.
Top tips, label every single school item with a black permanent marker written on the coat itself, in largish letters (so not on the label)
Ours are written inside above the label just under the collar.
Write it again in a 'secret' place, eg turn one sleeve inside out and write it. This is so that if you see another child in it, you can ask to check if it is your child's coat, and get it back.
Anything which has been clearly, obviously labelled with something which cannot be cut out is much less likely to go missing.
second top tip, always, always send them back in for anything forgotten. Come out without their jumper? Go back in and get it.
This means they will learn to find it and bring it out with them at home time, reducing the time it is available to be pinched, and they do get much better at keeping tabs on their stuff.
Initially mine only had one school sweatshirt, so if they lost it, they had to go in in a non school one. It did encourage them to look after them.
When I helped in dd2s class, one day at the end of school there was a pile of 25 cardies and sweatshirts in the corner (for some reason they all had to put them in the corner when not wearing them. As the kids lined up, I went through them, intending to give them out to the kids as they left.
Out of 25, one had a visible name. Just one.
The very next day I was waiting to pick dd up and someone was complaining about lost sweatshirts, so I told them this story, and pointed out that the one with a name wasn't their child's.