EuroNCAP ratings are harsher, so not really. It's mostly that the US system is based on SUVs and other behemoths. Look at the new small Toyota Yaris. That's what is required to get a good rating these days. Most newish SUVs doesn't even have the same amount of safety systems (like airbags between driver and front passenger seat).
I was speaking solely about regulatory requirements (i.e FMVSS) for selling a vehicle, not the NCAP programs. It is generally legal to sell vehicles with bad NCAP scores. For instance: the 2018 Fiat Panda met EU regulations to be sold but scored 0 stars on EuroNCAP.
I think it's not that the US is odd as much as each market is odd in a different way.
I remember one of the points of the failed trans-atlantic trade treaty was about handling where the stop lights should be on cars, because "safety" regulations differ.
Yes, the EU has high standards and differs from the US mainly on minor details.
Standards (or lack thereof) in much of Asia/Africa/S.America are on a whole different planet.
I guess my point is, not being approved for sale in the US doesn’t mean the car is shockingly different than many other cars in the rest of the world. You can find unsafe cars that would be illegal to sell in the US that say “Nissan” or “VW” on them just over the border in Mexico.
Every manufacturer builds cars to meet the specific requirements and needs for a market. In many countries, the requirements are low and the #1 priority is cheap.