I used to live in NY state. I remember reading about this group of motorcyclists protesting the states motorcycle helmet law by riding around at rallies helmet-less. Their argument against helmets was the usual “I’ll be dead anyway with or without a helmet” or “I’d rather be dead than a cripple.” Then at one of these rallies, while riding at fairly low speed, this guy hit a rock or oil patch or something, dropped his bike, hit his head and died. Medical experts agreed if he was wearing a helmet he’d almost certainly be fine.
And chances are he was dead without his head being caved in. That's simply the wrong model when talking about head protection from traffic dangers.
Where the helmet protects from small but fast-moving masses (weapons, falling rock or tools), protection of the skull structure can absolutely be the helmet's job. But where the danger is hitting a large mass like a car or a planet, the acceleration involved is the dominant problem and it will get you long before "caved in". Helmets provide a bit of a crumple zone that can certainly be very valuable, but at impact speeds that would be "cave in" without the helmet, even a crumple zone precisely tuned to exactly this impact (chances are that would be a wildly suboptimal configuration for many many other impacts) would fail to flatten the acceleration curve to survivable levels. "handsome corpse" wasn't aimed at helmets in general, it was aimed at the mental model of protecting from cave-in.
