There is nothing special about NATO interoperability. Military weapons worldwide are built according to NATO standards or Russian standards. Take your pick. It is true that NATO winds up being a big customer base, but there are other vendors in that market. Sometimes they fight against each other (e.g., the Falklands War).
NATO members have to have NATO compatible weapons, which Military Industrial Complex can supply . . . for $ BILLIONS.
There is nothing special about NATO interoperability. Military weapons worldwide are built according to NATO standards or Russian standards. Take your pick. It is true that NATO winds up being a big customer base, but there are other vendors in that market. Sometimes they fight against each other (e.g., the Falklands War).