No, I do not open food we haven't paid for. But, having said that, I will go to the till and buy one apple and let DS eat that while we're shopping. If we're at the end of the shopping he just has to wait. I also take toys, drinks, food etc if needed - ideally we go shopping just after he's eaten.

I was told off by my mother (a big one on denying her children anything they wanted) because she wanted to open food and give it to Liebling, even though he wasn't asking for it! I said no way, you don't do that and she told me off then was in a huff for about an hour. I do think it is important to teach a child that waiting for something and paying for what they want are virtues in society and things he should do.

I worked in a corner shop (no, not a large supermarket, a small corner shop) and trying to scan an item a child has already opened and eaten is a nightmare. Just pay for the sweet straight away, you're never more than ten seconds away from a cashier!