Remember the tiny Ford Ranger or Chevy S10? If they were produced today, they would be expected to have a very high MPG, which would require an engine unsuitable for the task as a truck.
The end result is that vehicles are forced to be unnecessarily large to get put in the class where low MPG engine can be installed.
It was caused by the legislature undermining progressive regulation. Congress was the one that required the EPA to establish different standards for “non-passenger automobiles” and allow SUVs to classify as light trucks.
It’s the only thing that saved the American car companies from bankruptcy post oil embargo shakeup so now its too entrenched a policy to remove.
https://tailoredtrucks.com/blog/2011-ford-ranger-towing-capa...
Cafe could not exist, and we would still be in the same situation. The root cause is too low fuel prices (meaning too low fuel taxes).
Motorcycling youtuber fortnine offers a good view on some other aspects of the situation. https://www.youtube.com/watch?v=YpuX-5E7xoU