are cards that dont have paywave or whatever really that common in the US? my bank cards have both had it

I'm in the US and I'm pretty sure all 5 (6? IDR) of my credit cards have supported tap-to-pay for a couple years now.

Most of my cards don't have it currently. Some do. I saw the new version of one bank's cards with it so I think when those expires or gets replaced it'll have contactless. Then it'll be about half of my cards without it.

I have over 10 cards, debit and credit, and I think only one or two don't support it.

I think most banks, but some banks are still slow to roll out. Also, having a contactless card right now wouldn't help my problem at the local Walmart. They have a bunch of old Ingenico devices that don't support tap to pay anyways. So even if my currently troublesome card had tap to pay, it wouldn't do me any good at my local Walmart. Otherwise, I'd just use Apple pay. Most card readers that support tap on a card also support Apple pay and Google Pay and all the other NFC pays (I think Samsung has their own?).

Also at my current job, I am the WorldPay guy. I work at a point of sale company and my area of ownership is integration into World Pay for payment processing at brick and mortar stores. None of our clients have tap to pay devices. They are all running 15 year old Ingenicos and plan to run them till they stop working. So as of right now, that is at least 2,500 stores in the US that I know of that don't support any kind of contactless payments.