In reply to Philip Cohen.

Acquirers aren't paying Apple a fee. Apple isn't really in the middle of any retail transaction...it's just a device sending track 2 or field 55 to the NFC reader. Online they're more in the middle - but still no cost to the merchant or acquirer - because they have a validation step for the data that comes out of the wallet before it gets to the merchant.
Issuers are the ones paying for the privilege of putting their cards into the wallet.