Maybe one day such machines will be in schools, but today it would not make sense to do something like that - kids do not have BTC wallets on their smartphones, and far from knowing how to use LN.
The problem is not only that someone would try to get free candy that way, but the bigger problem is that the machine looks like something that can be easily stolen. Again, on the other hand, it may be possible that the machine can be attached to a substrate or wall - there are small crypto ATMs that use some kind of lock mechanism that prevents someone from just taking them away.
Someone really tried to make the ATM noticeable, it's hard for anyone not to notice it even from a greater distance