What do you think about the comparison of uniform rules, make-up, jewellery, trainers, etc- as compared to healthy eating?
If one child is constantly breaking the rules (and I imagine it was with other items apart from mini cheddars on other previous days)- it causes all sorts of problems with the other children who will go home and nag -saying well Jonny brings crisps, mini cheddars, rolly pollies, whatever. It is all very easy to throw hands up in the air and talk about Big Brother- try and imagine how allowing one child to break the rules leads to problems with other children. You can't have a rule, be it about nail varnish, or short cropped tops, piercings, extreme hair dos, etc- and allow some children to repeatedly break the rule and get away with it- or it leads to others doing the same and pandemonium.
As said, I'd rather a school was stricter about healthy foods than some of the rules on others mentioned above, which do not have such a strong effect on personal health, but even more importantly, on the health of the nation and future health budget going mostly on food related problems.