I'm not sure I agree that unicycles are safer than roller blades. But that's probably because I am comfortable on roller blades and don't know how to unicycle, so for me, the opposite is true.
As both an extreme unicyclist & rollerblader, unicycles are actually incredibly safe. More safe than a bicycle. The top speed is very slow comparatively, and if you fall... You fall on your feet. Forwards? Feet. Backwards? Feet. Sideways? Feet. If your feet were strapped into the pedals (like rollerblades...) it would be a deathtrap.
Trains and planes and others are a bit wonky for this chart. If I needed to take get to work, train and plane immediately resort to walking the entire way (unless get in a car, on a bike, fall just after). So while traveling across the country for a trip may be convenient on a train... Wait, unless I only have the weekend or a short work trip/vacation, because then it would take to much time and be inconvenient. Tried to find an example. Travel to Las Vegas from Nashville. Plane, ~3 hour flight plus let's say 2 hour travel and airport bs. So 5 hours there, 5 back. Driving: 26 hours (each way). Walking: Death by dehydration in desert. Train: not even listed as there was no routes.
