Are Singapore school canteen vendors being pressed too much?

I understood the rental in primary school canteen is very very low. Let’s say it’s $50 dollar per month, school canteen vendors are being pressed to put the price of serving rice+meat+veg+fruit for $2.00 to $2.50 and its at least $3-4 dollar lower than market. They justified it that because rental is Low. If we treat that $3-4 off as a way of rental, one stall sell hundreds plates per day, it will be totalled to $300 per day. That’s at least $9000 to $12000 per month as “rental”. Not even mention that canteen cannot operate during school holidays/weekend.

Why do we have to press them on prices? Don’t we want to make sure children eat good proper meal in school?