I use tap to pay probably 90% of the time in the US these days. The 10% of holdouts are either very old mom&pop shops (though many of these have largely migrated to Toast or similar systems) or… massive retailers who didn't want to give up control. (Or various restaurants who don’t have a payment terminal to bring to you.)

For example, Walmart tried to invent their own mobile pay solution instead of Apple Pay when Apple Pay came out a decade + ago. They didn’t want to loose on the extra fees Apple charges.