Presumably the people than can afford iPhones you loving handicap
obviously. so what should the school do- remove eligibility for children who own iphones?
but the point is that if you can afford to buy an iphone but can't buy a school lunch for your kid, then you shouldn't buy an iphone
it's not the school's job to instruct parents what they should or shouldn't buy. if parents have a budget of $1,000 to spend, they can 'afford' to pay for child's school lunches, but then you're removing those parent's ability to pay for added expenses, save for retirement and other stuff.
if we operated on 'if you can afford to pay for something, pay for it' the moment you break your leg or you get a bug infestation or some other expensive event happens, you'll be broke and unable to pay for it to be fixed. A safe amount of savings would be like 15,000$ a year in order to plan for those extra events and other things. That doesn't include the new iphone or child's school lunch money