Hi - unfortunately glass can and will develop light scratches from use of the wipers over time. There are glass polishing pads and special glass polish that some say can remove these very light scratches, however I have personally not had great results with these products in the one time I have attempted it (so I have little to no personal experience). Glass is very, very hard relative to what we are used to when it comes to correcting defects in automotive paint, so removing even the faintest of scratches can be a real challenge on glass.
CarPro Ceriglass
Glass Polishing Pads
Hope that helps! Let me know if I can answer anything else for you.
-Zach