JeroenE You have to see it this way: The bank charges a retailer costs for each pin transaction, say 0.05 cents.
Apple charges 0.015 cents for using ApplePay, leaving the bank with only 0.035 cents instead of 0.05 cents.
That seems small, but at 70 billion pin transactions per year that can make a difference. Suppose that 10% goes through ApplePay, then that's 7 billion transactions, times 0.015 cents ... then we suddenly talk about more than 100 million euros if I calculate it just as quickly.
Since bank transfers are free for consumers, the bank suffers a loss because they have to pay Apple, but cannot charge fees. That is the same as with iDeal, so it makes little difference to that extent.