SlowNPC

used to alert the rider that the software has overridden user input

I think this is the whole point. Riders were asking more of the boards than the boards could do, and when the board was unable to comply the rider would lose their balance. Haptic feedback tells the rider “nah, not doing that” so they’re aware the board isn’t going to do the thing and can adjust their balance accordingly.

Look into cluster b personality disorders and cptsd. This behavior sounds like “splitting.”

I’m not a mental health professional, but lived with someone who was later diagnosed CPTSD, so I ended up doing a bunch of homework on wtf was going on.

I suspect it has to do with legal compliance. Only available in US = only needing to comply with US law.