It’s the illusion of control. We all know logically that the best driver in the world can still be killed by a really negligent fellow driver, but people don’t really internalize that. If there were a giant hand that sometimes killed people on staircases, people would be more worried about staircases than they are now, even though plenty of people already die on them (about a tenth as many die on the stairs as occupants of cars die in accidents). We know what the risk factors are, and we can reduce our own risk by using a bannister, carefully clearing snow or ice from outdoor steps/making sure there isn't a loose carpet on indoor steps, and arranging our homes to use stairs less frequently as we get older. Doing those things makes us feel like stairs are less dangerous, even though our statistics reflect a world in which people already know to do those things.

It’s why aneurysms are so scary to some people- we don’t really know how to diagnose what causes them until they’ve already happened, so they feel random to people

Does it pick one person randomly on the planet then travel there in one day? Then you'd probably see it a few times moving from person to person. Especially in high population areas. It would be a fairly common sight traveling between China and India. It would definitely be unusual to witness a crushing or to know anyone who was crushed.