> What the heck is that all about?

Tax fraud? I've never seen a card reader in a restaurant (here in europe) where they couldn't either enter a completely arbitrary amount to pay, or add a tip.

That's not a thing. Americans universally pay for restaurant meals on cards.

It was probably an issue with that particular merchants POS. Merchants have very little incentive to update their POS systems so technology changes are very hard to get rolled out. Especially for smaller merchants which many restaurants are.

It’s a network effect thing. Because tap to pay wasn’t supported by the POS vendors US consumers did not get much improvement in experience because of it, so there wasn’t demand from merchants. With Apple Pay there is a huge improvement for consumers (not having to carry the credit card) it has finally forced merchants and their supporting POS vendors to support it.

Between that and the disruption in the POS market the iPad (and similar devices) brought, POS vendors have had to become more flexible.

Re: Apple Pay acceptance, some of the big chains took the chance to push hard for their own payment solutions ("Walmart Pay") in the hopes of not having to pay card processing fees anymore. Obviously the market has spoken and one by one they've been giving up.