Imagine a ½ inch wide by maybe a 1/16 deep
Anything that big, I would guess anyone in their right mind would agree that it is beyond "repair" and into the replacement category. On a car windshield, anything 1/16" thick, .0625", or nearly 1.6mm is probably a serious compromise in windscreen integrity. Remember an auto windshield/windscreen is comprised of two layers of glass, each about .125" laminated with a vinyl interlayer.
The reason I asked the question is my daily driver. The glass seems to be incredibly soft; I've got very minor scratches on it here and there, some of my own doing inadvertently as I used a fine painter's razor to remove some incredibly stuck on bugs and related that even solvents and bug remover didn't budge. Sure the razor got it off, but in the right light now I see some annoying scratches, despite my gentle use. Last week, the metal reinforcement must have popped out of the passenger wiper while I had lent the car to a friend, and in a rainstorm that metal running across the windshield has left an arc needing polishing.
So, I think a good polishing is in order, but based on Stick's experience might be hard to find…or expensive, or both.