Clarification for non-Americans. Aka "America is doing something fucking stupid, again"

In the United States, crash safety testing is left up to the automakers for the most part. The NHTSA only has the budget and resources to test "the most popular vehicles sold" to ensure that the manufacturer simply isn't LYING outright

As such they've publicly stated

“While it has certainly created a lot of buzz, it’s unlikely we would invest resources to test it unless it were selling in numbers comparable with other popular large pickups”