A key difference though: someone walking can stop in place and potentially work around a collision in a very limited time. I'm imagining someone flexing in to a

A key difference though: someone walking can stop in place and potentially work around a collision in a very limited time. I'm imagining someone flexing in to avoid a small kid they didn't see coming for instance. That's pretty manageable when we're walking, but basically impossible when riding a vehicle (at best we stop within the machine's braking distance, including our reaction time until pushing the right button). Then when a collision occurs, it will be the luggage's hard surface hitting first, compounded with the weight of the rider on it. Compared to person vs person collision, that probably hurts a lot more. Same way it's worse to get hit by a cart than by bumping into someone.