In reasonably dense U.S. cities, people walk into the road outside of crosswalks all the time. Even in suburban areas, it's normal to cross like that in residential areas. But suburban areas are often crisscrossed by 30-50 mph streets where crossing the street outside of crosswalks (or sadly even in crosswalks, really) is dangerous. This is partly because of the speed limit. But also partly because there are few pedestrians (points of interest are far apart so people need to drive everywhere), so drivers are relatively reckless.

I'm not convinced that the pedestrian outside crosswalk omission arose because of U.S. car-centric thinking. I think if any software engineer working on the project was told that their autonomous driving system wasn't watching out for these pedestrians, they'd be horrified. In fact, probably many of them were already horrified at how poorly their system was performing in general, and yet management still deployed the software in actual physical cars.