If forced, I could probably align my purchases with only those vendors who use Apple Pay. But I choose not to. I would consider the USA to be a big region where it might be thought that Apple Pay is ubiquitous.I expect you will find a correlation between iPhone only carriers and regions where Apple Pay is ubiquitous.
Once you realise you can and do spend weeks and months without having to use a card or cash, leaving the house with just a phone becomes the default.
Can you please tell Walmart that?
Home Depot finally came around and started allowing tap to pay though. I still use cards, even though all of my cards are on my phone. And I do realize what you've suggested as a realization. But I still choose to carry cards. I don't hate Apple Pay. I use it sometimes, but I just prefer tapping to pay with my card I guess.
This places me out of your norm I suppose.
PS. I also still carry cash, just for those situations where paying with my phone or a card isn't allowed or convenient. Plenty of places in the US that are still cash and carry.