yes, there could be another side to this story.
what can be sold in school canteens need to be approved by MOH. pricing needs to be approved by Principal. any increase needs to submit request and justification. food poisoning case in other schools may end up having that item banned islandwide.
it's not as easy as some might think. my mother had a stall in a secondary school selling hot drinks and sandwich snacks before. increase 5c also need approval. school staff, especially the senior ones always like to take advantage like bringing own big mugs for their drinks, add toppings for their snacks but pay standard price... the type ai pi ai qi, ai tua liap ni.... students much better customers.
but as always, there are black sheep too. for example, some stallholders may sell prohibited food "under table".