I think rules re school Uniforms, piercings, etc, should be adhered to, but I still think inspecting lunch boxes is beyond the school's remit.
I Had a discussion on more than one occasion about the introduction of uniform at DD1' s primary school - the HT liked them to "express their individuality", I and other mothers wanted a uniform. He did not have children so he did not have the problem of of a six year old girl expressing her individuality at 6.30 every morning.
I would object to a dinner lady, teacher or whoever poking through my child's lunch box.
I said on a different forum that free school dinners of good quality are a good idea, even though some people can afford them, perhaps that is the price we have to pay to ensure that all children get a wholesome meal at least once a day.
Parents-in-Law. What do/did you call them?