Probably because they suck. They scuff up and look like you're looking through a dirty window. Takes a state of the art display, and makes it look like it was dug out of a 50s era landfill. Tempered glass is almost as cheap as free. When it gets too cracked, pull it off and install another. I work in a harsh environment, and my glass protector I stalled 1.5yr ago has a single crack that isn't so easy to see. If/when it gets too bad, I'll install the other one that came with the case I bought. The case + two protectors cost the princely sum of $11.