First, traffic circles are rare here, and grid patterns more common, so we have many more simple intersections of roughly equivalent roads. This likely set a precedent where the default choice was simply to avoid trying to determine who should give way, and just tell everyone to stop and then follow a set of rules that were dependent on the moment. Fuel economy would not have been a concern at all.

If it doesn’t actively cause problems, even a sub optimal standard can still settle in. Then, once cultural inertia takes over, it can literally be dangerous to try to change ingrained driving habits, and even if it’s not strictly dangerous, in a large country with vast swathes where virtually everyone drives, simplifying the decision tree is important for traffic flow.

For instance, this is not directly related to stop-vs-give-way, but it’s illustrative of how standards become sticky even when there’s s better way. There is a very busy at-grade intersection near where i live that became infamous. It has a combination of having multiple lanes on each road, speed limits nearing the top of what’s allowed on “normal” roads (ie not a freeway/motorway), large numbers of young drivers, and large numbers of wealthier drivers. It became known, hyperbolically, as “the most dangerous and expensive intersection in the world” because of the large number of accidents that involved expensive cars, and it was a nightmare to navigate. The insurance companies and the traffic planners wanted to try to fix it.

So they did all their studies and spent millions to turn it from as signal-controlled intersection to a “Michigan Left.” Drivers were confused and angry and the lack of understanding meant that people hated it. They were confused, so there were still a good number of accidents, many of them at higher speed since drivers who did understand the concept would not be ready for someone turning against traffic. Many people simply avoided it, clogging nearby routes in a way that more than mooted the advantages of the new layout.

In the end, the government left the new infrastructure as an option, but reopened the old turn lanes and set the signals back. An objectively better layout in ideal situations was an utter failure when actually imposed on the American driving public. Using more stop signs than we “need” is similar in that people expect a certain behavior and driving habits are built around it, and switching to the English system would probably create as many problems as it solves, while also being expensive for whichever generation would have considered it.