Currency is fungible, dollars,euros,pesos,escudos,or whatever.
If my customers want to pay in any legal currency fine with me..
Pizza Hut in Mexico City accepts dollars.
mmmmmmmmmmushrooms
There is only one legal tender in the US to settle debts....
Mexican peso's do not fall under legal tender here...
I do believe that the chain is violating US law. If they set themselves up as a registered currency exchange (highly regulated) then they could exchange the peso's for dollars.....then for pizza....
Even US States are no longer allowed to print currency any longer...only the Feds...