Locally grown fruit tends to be much cheaper than fruit from say, The Netherlands, a big producer of fruit in Europe. This is, of course, obvious.
However, processed crap from somewhere further afield may actually be cheaper than the Dutch fruit because it uses crap ingredients made cheaply for a shoddy product. This means that groups with very tight budgets can afford to buy however many crates of the processed junk to feed to their consumers, in this case children in schools. The dutch fruit may even be too expensive to buy enough of, meaning it isn't really an option.
Local fruit, being cheaper than the dutch fruit, can be more readily bought within a strict budget, making fresh fruit a more widely available thing.