When I was in school the less well-off kids got their lunch free. There was definitely no equivalent to a “marker” the linked article mentions, unless you include the lunch ticket. I was actually kind of jealous at the time, I didn’t understand why I had to pay when I didn’t bring my own lunch and they didn’t.
Singling out kids because their parents can’t afford food is kind of fucked up.
I leave on time, how is that an insult? I’d be much more insulted if someone asked me to work for them for free. That’s what unpaid overtime is.