I think all engineering has safety factors of 2 or more. Maybe with the exception of aerospace (mostly space) where materials might be at the limits of what's possible right now so the safety factors are much reduced.
reply> I think all engineering has safety factors of 2 or more.
replyNot even close.
For example, a BMW X5 weighs about 2200 Kgs without passengers, and it's GVWR is 2800 Kgs.
If you have five people and heavy bags, you can comfortably exceed the GVWR. You can absolutely break control arms and suspension components in that scenario if you go over a speed bump or hit a pothole (which are real things that exist in the real world, like people doing something unintended and crashing software).
If this needed a 2x safety factor, there would have been no way to build this car.
Even the toughest cars like land cruisers are limited in this way.