IIRC, in the UK, when Debit Cards were first introduced, the merchant and transaction fees were on a par with the Credit Card charges, before they were reduced due to protests by merchant and consumer groups
Once Apple have vetted an app, it should not be too onerous for them to track and vet functional changes between versions, and if at all, have some sliding scale of capped charges to recoup their overheads.
Biting the hand that feeds IT
