Giuliano Interesting and thanks for sharing. Did you use the Mastercard Debit? I travel in the US regularely too, and I haven't found significant number of places where it doesn't work. Sometimes it doesn't work; but then again sometimes my other card(s) also don't work. It seems to be a bit random there unfort.
I usually travel to NYC and/or SFO, and never rent a car. Hotels, restaurants, bars, airbnb, uber, atm's, metro machines, have never been an issue for me.
Thanks for explaining!