None of these labeling decisions are made lightly. Tons of market research. Then meetings. Months of meetings. Then more market research. Then more meetings.
Imagine how both Shell & Mobil decided that gasoline truck owners were looking for their own oil. Because macho truck & SUV types don't want to share oil with a Prius or Hyundai. Even though most cars and trucks have been using the same oil. Now they will continue to use the same oil, with different labels. It's like all those brands of dry pasta & frozen vegetables being sold with different labels and different prices. We all know that a bag of frozen peas is the same, no matter which you buy or how much you pay.