I’m not sure that Google necessarily failed with glass. Too short of battery life for sure. Then there was the whole creepiness factor of having ‘glassholes’ walking around recording everything, and everyone they saw.
I consider Google to be the public, commercial arm, of the NSA.
Google did not fail technologically. They failed by not grasping the social factors. They are tone deaf there. Apple excels on social factors. . . Apple understands users and user interfaces. Google is geeky. . . and GoogleGlass was a big hit with geeks. It was a big turn off with normal people. Apple would have never have released it as a product, because they understand that difference. It would have been one of those projects that Steve Jobs would have said "Neat, but NO!" to.