You are correct, they do need to be zeroed in for a preferred distance. That said, 1-inch variance on 100-feet is more than enough for most people. Very few home defense situations are happening at 100 feet, and even still you have a one-inch variance... that's pretty darn good and I don't think most shooters can do that on sights, let alone a point-and-shoot in the dark.
Why the huge price tag in something that's mass produced with no hand fitting?
Because they can get it... and because the product is that good. Until another company starts making easy-to-fit grips with this kind of accuracy, they can charge whatever they want.