Try a search for "does apple pay increase interchange card fees?" and read the
many posts you find. Your post implies that all of those others are lying.
There are even services popping up trying to help small business minimize the added costs of accepting Apple Pay. For example:
https://koronapos.com/blog/apple-pay-fees-for-merchants/ (I have no relationship with them, they are just one of many that popped up in search talking about this topic).
I don't fault Apple for making money any way they can. But clearly SOMEONE is paying Apple and whoever that is is not doing so out of generosity. Ultimately, whoever pays the extra for Apple to get that cut eventually gets to the merchants, who then "cover" the added cost with higher prices... or refuse and thus, don't accept Apple Pay. None of the "middlemen" are going to take the hit to give Apple that commission. If anything, they will want to make more themselves (too).
I'll grant that it is indirect (like carriers offering "free iPhones" doesn't mean that they are actually free either) but I just do NOT believe it is solely out of "fraud" savings. If anything, big bank enjoying any such savings is going to keep it for themselves (that kind of maneuvering is HOW big banks have gotten "too big to fail.") And if the only way to profit (too) on such savings is Apple Pay-like tools, big banks will roll out their own versions of Apple Pay to cut an ongoing fee to Apple out: Goldman Sachs Pay, Morgan Stanley Pay, etc.