I guess some people are paranoid about glass breakage. I haven't broken a window since I can remember, so I don't worry about. Mine has glass. I didn't do safey glass for a reason. When safety glass breaks, it tends to completely collapse, which would free all of the bees. When window glass breaks, especially when framed, it tends to crack into large pieces which quite often remain in place, containing the bees. The large shards can be more dangerous if you really think it might get broken.