Earlier quoted context omitted.
I don't think AR has flopped so far, but when it's used well it's not perceived as AR. For example, my car has a rear camera, which overlays where you are going depending on the position of the steering wheel. This is reality augmented, but since it feels so natural, nobody thinks about this as AR.
I disagree that the steering guide lines on a reverse camera are AR. A key aspect of AR is that it is environment-aware. An image overlaid on a video is not actually aware of “reality” at all.
Some go a bit further and overlay imaginary barriers based on the distance of objects near you: https://cnet2.cbsistatic.com/img/gvHEEq5aZgDanoLARwsAzNN66Qk...
But yeah, in general this application doesn't have the kind of impact people are talking about when they say mainstream AR.