Usage of debit cards for payment

Why does the payment system only accept the credit card ? Most of us use debit card especially college students don’t use credit card. I couldn’t use my payment info to but iCloud storage and also subscriptions to apps because of this lack of choosing type(debit)of card for payment Method,though it’s a small amount to be paid per month for storage .anybody carrying an iPhone can afford to pay.please provide us the option of debit system for payment methods .