Primary Teacher here.
Absolutely parents steal things. And frustratingly, I find it's often the parents who can most afford things that tend to do it.
Prime example from last year:
Child A: single mother who doesn't work, so relies solely on benefits and had been open with me about how they struggle financially.
Child B: mum is SAHM by choice, dad works and occasionally does drop of in suit before going to work. Obviously I am not privy to their finances, but they certainly appear to be one of the more 'comfortable' families in the deprived school I work in.
Jumpers got mixed up on the carpet at the end of the day. We were 90% sure because of where children were sitting that Child B had gone home with Child As jumper.
Child As mum upset and worried because she can't afford to replace it. We reassure her that we're pretty confident we know who it has gone home with, and as it is named it should come back to school.
Catch Child Bs mum and very politely say 'we think Child B May have accidentally gone home with Child As jumper. Please could you check and bring it back if you find it?' Child Bs mum comes back the next day and says she has looked but it is not at their house.
Two weeks later the children are getting dressed after PE and clothes are scattered everywhere. I pick up a jumper to give back to owner, and it has an iron on name label with Child Bs name on, ironed on to the tag in the neck of the jumper.
Only, the iron on label was peeling up slightly at one end, revealing writing underneath on the actual jumper tag. I could see the last letter of Child Bs name so ripped off the label, and lo and behold, there was the missing jumper.
I absolutely understand that things get accidentally get mixed up and go missing, especially in primary.
But to use such an opportunity to your advantage and actively decide to put your own child's name over another child's to claim their belongings as yours is despicable behaviour IMHO. Especially when the child you are stealing from is so much more in need than you.
Still makes me angry even now 