> And companies like Visa, Mastercard, American Express, &c. arose initially from solving a real need. Before these companies came into existence when you traveled you'd have to take cash, or traveler's checks or some other nonsense. Today you can, at least as an American, just walk in to the subway in just about any country and tap to pay. Need a coffee at Mt. Fuji? Easy. Buying a bottle of Calvados in some remote area? Yea just tap to pay with your Mastercard.

The reality is more complicated.

I have had Visa or Mastercard being refused in other countries by some retail outlets / institutions.

In fact I never travel with only one card from a single bank because I always want to have a backup. And it is not really Visa vs Mastercard because I have had occurences of having 2 Visas, one of which would work and another would not on a specific shop for no obvious nor documented reason.