Spurious correlation. Both pork and beef have been used in English (both American and British) for centuries. Both beef and pork refer to the meat from multip

Spurious correlation. Both pork and beef have been used in English (both American and British) for centuries. Both beef and pork refer to the meat from multiple subspecies while fish and poultry are considered game/sports meats and named for the animal 'bested'. You'll note many old recipes simply say "white fish" to denote cod, herring, haddock, pollock or any number of firm, white-fleshed fish. This custom persists today.