Why does the slotted screw persist?

This is a question about screws, yes, but also more generally about the persistence of inferior technologies.

I can see why slotted screw heads were the dominant technology for a long time; with old manufacturing methods, it was super easy to cut a slot across the head of a screw, and a flat screwdriver is easy to form. But they positively suck. Nothing keeps the screwdriver from slipping out of the slot, so it usually does (multiple times). It’s extremely easy to chew out the slot and render the screw useless, just by tilting the screwdriver slightly off-axis.

We have vastly superior ways of making screwdriver recesses in the heads of screws these days, and they’re all formed by essentially the same process. Phillips-head screws have existed since the 30s. Now we also have square-drive, hex, and Torx, all of which beat the heck out of slotted screws. Phillips-head screws and drivers are about the same price as slotted. Pretty much everyone who has a straight screwdriver also has a Phillips screwdriver.

Why are these damned things still around? Who would care if they vanished? Am I missing something here?