But originally the App Store was leveraging their existing payment infrastructure e.g. the one they use for iPhone sales. Purchases and invoices were done through SAP which was manually configured to support those price points. It's why you saw weird behaviour e.g. invoices for free app "purchases" and largely the limitations of that system drove what they could and could not do.

Perhaps they've done an overhaul for this system or migrated to a custom built one which is what has enabled all of this new functionality.