The difference isn't between America and the rest of the world. It's between Australia and the rest of the world. The Honda Insight gets sold with a 20 weight both here and Japan. Same for the Prius. When they arrive in the EU, they start with a factory fill of 5w-20, but I'm not sure the recommendation. Why anyone would pay the premium for an Insight/Prius and run a 40 weight in it.....
An argument could be made that recommendations for 5w-20 are pretty rare outside of NA and Japan, but that's due to two easily explainable factors. First, our government run fuel efficiency ratings mandate the use of the same oil during the tests that is recommended to end users. So manufacturers are forced to recommend 5w-20 here, which creates the demand that wouldn't be seen if they could run the tests with any oil they wanted and still recommend 5w-30. Second, we have a lot of demand for all petroleum products, and a very large refining capacity... so we have the supply to meet the demand.
As for the Hilux, that's a truck. And truck people loves them some thick oil. That's true here too. I'm sure there's Tacomas all over running 5/10w-40.