The American standard is logical: command and "and" are interchangeable: "A and B and C" "A, B, C" "A, B and C" The Oxford style is inconsistently, doubling

The American standard is logical: command and "and" are interchangeable: "A and B and C" "A, B, C" "A, B and C" The Oxford style is inconsistently, doubling up command and "and" in the last item. This is silliness. There are two styles because English grammar is a not a precisely logical formal language. Neither side is wrong; English is ambiguous.