Some things are relatively easy to refund via Apple, but not all of them. It's nearly impossible to get a refund for in-app purchases, gift cards, balance top-ups, auto-renewing subscriptions, redeemed digital goods, and so on. Coming from the EU, if I paid for these things directly with a credit card, I'd be able to get a refund in line with our consumer protection laws (if the item was sold deceptively, if it has a fault, if I am not satisfied for any reason within 14 days) that cover more or less all digital purchases - no problem.
To borrow your words, Apple's system is taking away trust. I like the refunds my European bank offers me because it operates under consumer-friendly laws. I don't trust Apple's refunds.
Anyway, opening any system to more choices for the consumer cannot decrease trust. If the consumer trusts the original payment option, they can use that. If that is not provided, but the customers don't trust other payment methods, the app won't make money. The market will soon negotiate so that the payment methods that customers and sellers find acceptable prevail. Apple fears it won't be their extortion (I mean payment system), and rightfully so. Aside from the Stockholm syndrome, there's very little reason to use it.
