There's at least some difference in design and requirements due to different assumptions about how high one needs to go on external rig, equipment in use, and fire codes.

None of it insurmountable but essentially means european vendors would need to make US-custom trucks which wouldn't make for cheap option at least for starters

I think there are some differences in approach and philosophy. Some are probably real and essential and some are more culture in fire service.

There are most certainly online discussions at great length on the topic.