When I look at the types of screw drives, I see... a lot.
History probably explains why so many existed, but I fail to understand why some still exist today.
For example, compare Double Hex with Spline .
It seems obviously clear to me that the Double Hex has a higher chance of wearing out or slipping, and it seems to have no advantage whatsoever.
Or for example, compare the usual Hex Socket with the Robertson .
Again, the Hex Socket appears to have a far higher chance of eventually wearing out or slipping, and again, no apparent advantage.
So why do these keep being used? Do they really all have at least one physical advantage over the others? Or is it a cost thing, or is it something else?