@abid...i believe you that it happens but i wanna know how it is done. simply stated...buffing is the process of rubbing, polishing or both of a surface to make it clean, shiny or both etc.
buffing can be done by hand with a cloth, towel or with the help of an electric rotary buffer. unless you have some very hard and old dirt or scum on the windshield..take it to a professional...but if no...do it yourself.
and i say again...no type of buffing usually removes scratches...cuz a scratch on a glass surface is not the same as a scratch on the body of the car...on the body...you have the paint and then the clear coat on top...which has a depth (micro mm) but that is not the case on a glass...its surface its just bare...so a scratch takes place in the body of the glass.
the best to test it yourself....if the guy doing the buffing can remove scratches by just buffing....give him a hug.