The Oxford comma, I believe, is generally referred to as the serial comma in the States.
When I took English back before the Beatles, I learned to separate all the items of a series with commas. Thus it was mandatory to write: “Red, White, and Blue.” As the years passed there was a tacit movement to eliminated unnecessary punctuation and it seemed reasonable. Go back and read some of those 19th century authors with their commas and colons and semi-colons. Now notice that when I write a series using the conjunction “and” I do not require any serial commas. Going back to the original phrase, the use of the final serial comma is redundant. Thus it seems logical to write: “Red, White and Blue.”