The Hacker News thread critiques an article on Apple's payment systems, primarily focusing on the confusion between Apple Pay and in-app purchases (IAP). Commenters point out the original article incorrectly uses "Apple Pay" to refer to IAP, Apple's system for digital goods that takes a 15-30% commission. Apple Pay is a digital wallet allowing users to pay with cards already linked to their Apple account, with no extra cost to merchants. IAP, however, functions as a "merchant of record" where Apple handles taxation and refunds, taking a significant cut. The discussion highlights that Apple mandates IAP for digital goods within apps (with some exceptions), while Apple Pay is optional for physical goods or in-app purchases. The comments criticize Apple's restrictive IAP rules, arguing that allowing competition between IAP, other merchant-of-record solutions, and direct merchant payments would be beneficial. The analogy to Costco's exclusive card agreements is debated, with some arguing it is not a valid comparison.