For this exercise, we'll use the kit EF-S 18-55mm lens.
It's a cheap (affordable for everyone) lens with good+ IQ. No matter how we look at it, it's an 18mm lens on the wide side. Even though it's made for crop bodies, the lens is an 18mm lens. As it's built for crop bodies, it gives an efov (effective field of view) of a 28mm on a 35mm format (aka full frame). Not so wide anymore. But even still, it's an 18mm lens. Everyone agree so far? Good.
So my question is, to get an 18mm fov on a 35mm format, you have to buy something for 4 times the cost (at least) of the 18-55mm. Yes, I realize those are L lenses, and that there are other aspects of those lenses that contribute to the cost factor. But, why doesn't Canon (and other manufacturers) just make the 18-55mm (or similar) in an EF mount, rather than the EF-S mount? I would think the optics would be the same, just maybe different spacing inside the lens body, and probably need some other engineering adjustments to make it work for a full frame, but IMO, the price shouldn't have to be 4x as much, or even 2x as much.
As I don't build or design lenses, I'm hoping someone here can explain why a lens like the 18-55mm isn't made for FF at a reasonable price point.
Back in the days of film, there was (essentially) one mount made for a brand's current body line-up. And lenses of 24mm or wider were always at a premium. But Canon/Nikon/etc., by producing the 18-55mm line has proven that that premium was really just marketing. If it wasn't, the kit lens would be a EF-S 28-70mm (non-L), and the 18-55mm would be $800+.
It seems that the manufacturers are trying to carry through with the 'wider than 28mm premium', while showing us the premium is unnecessary.
What say you?