If we're still speaking about AR glasses, no current technology can make the images more opaque than the screen itself. So if the screen itself is transparent, whatever you draw on it with light will be at best as opaque as the screen - so, still transparent.
Because AR glasses, by definition, overlay an interface onto the real world that you are seeing through the transparent glasses.
VR glasses like the VisionPRO can add a video stream of your surroundings, but they are physically opaque and thus don't suffer from this limitation.
But why does the interface have to be transparent? Why can't it just be opaque then disappear when not needed and/or be placed in the periphery?
If we're still speaking about AR glasses, no current technology can make the images more opaque than the screen itself. So if the screen itself is transparent, whatever you draw on it with light will be at best as opaque as the screen - so, still transparent.