1. An iPad can cost more than a Mac Mini (especially a used one).
2. You don't need a Mac. Only access to one. Maybe in the school's library, company co-op, or as a server in the cloud of some charity. Someone or some company does need to enroll in Apple's dev program though, which requires a credit card in some countries.
When was the last you were able to install software on a school computer? if only...
They would spend so much time on the machine that it would almost have to be theirs.
Mac Mini+Monitor+Accessories etc etc.
I can see your point though.