Employees skimming off the till?
On the merchant end of things, accepting card payments reduces their exposure to risk from theft (both internal and gun-in-your face type). For the big guys, the fee is in the low 1%.
But you're right about the lack of transparency. If card fees were required to be itemized separately, the whole dynamic would shift dramatically. But as far as Apple Pay and similar systems are concerned, the 0.15% is bitten off the banks' fee already, and the price of the transaction isn't based on cost, but on value. As a thought experiment, imagine if Apple stopped taking a 30% cut of app store purchases. Do you think that $0.99 games would be priced at $0.69? Probably not. I think the same is probably true of merchant fees--that they're not going to--on average-- increase by 0.15%.
We'll know for sure in the next several years though.
Now, imagine a poor or homeless person with bad credit that pays in cash, debit or non-rewards credit card. That person is paying more for the same things compared to you at the store and gets none of those perks.
>As a thought experiment, imagine if Apple stopped taking a 30% cut of app store purchases. Do you think that $0.99 games would be priced at $0.69? Probably not.
Even if not, the developer has 30% more to spend on developing the app, resulting in more and better apps. Apple, meanwhile, is buying back stock and giving dividends with all the extra cash because they don't know what to do with it.
This is like how people are made to think a new flagship smartphone from AT&T costs them $199.