Do you really pay online, like flight tickets, with your debit card, that works? I try regularly, it never works.
In shops the main issue is that the terminal they use can only read Apple Pay credit cards. If you’re using you’re banking app to pay wirelessly, it may fail to work with some merchants.
It’s not that they don’t want to accept it, the physical card would probably work (I don’t physical cards anymore), but the system is rigged to favor credit cards it seems.