Well in the 70's, it was law in Ontario that margarine could be white or very yellow but not butter coloured. However, in Quebec, it could be butter coloured. We had family who lived in the Ottawa valley, where the margarine was smuggled across the boarder. We always had massive quantities of butter coloured margarine in our freezer.
My granfather lived in Wisconsin and his father got caught for yellow-margarine smuggling over the (Illinois/Wisconsin) border
I remember margarine ads in the 1960's, when apparently they could not say
the word 'butter.' They could allude to it: "Tastes just like the high-priced spreads!" The only "spread" that I knew about was my mother's bedspread. Why would anyone want their margarine to taste like cotton chenille?