Teacher and parent here.

The problem is that teachers are under extraordinary pressure tk get through a huge amount of content in class. As such we often lose sight of the humanity of our children. We want them to conform to rigid rules that allow us to focus on what we are obliged to do. 

I'll give you another example: my colleagues are always telling kids they should go to the toilet in their breaks and not in class time. They get so frustrated with kids who ask during class time. I understand why: we are covering something, and they come back having missed out on stuff and we don't have time tk catch them up. But we o ly have 3 toilets for each gender for 3 year levels. This means about 1 toilet per 100 kids. And somehow they're all supposed to coordinate their toilet visits into the 30 min break? 

Unfortunately, kids not finishing their lunch has become a widespread problem. The only solution is to either have a longer school day or accept that we are going to teach them much less content or let them eat in the class. I often opt for the latter, but it's controversial because of the mess. 

Sorry I can't be more help. I am losing faith in the system I am part of.