The explosion in the number of GLOCK Gen 3 clones has apparently been led by some patent expirations. I know nothing of patent law, but I do remember when GLOCK defended their IP quite vigorously. I’m sure S&W remembers as well.
That doesn’t seem to be the case with Anderson, PSA, Adams Arms, and many more who are doing their own thing with Gen 3 Glock platforms. One company doing something different with the familiar platform is Matrix Arms who’s doing things with their MX19 pistol that are breaking the mold.