Windshield haze

I bought my sisters sienna. She lived a couple miles from the coast and she either ran the wipers with sand or salt on the W/S or let the blades get overly worn. I was considering buying some cerium oxide polish to try to polish out the fine scratches. I tried to find a local glass man to do it for me, but they don't do it anymore because of "liability". Each person gave me a different reason that it's not a good idea, but none sounded plausible. These are fine scratches that can't be felt with your fingernail. Has anyone had their W/S polished successfully? I think the glass people want to sell me a new windshield.:shakehead

An update for anyone interested. I got some cerium oxide glass polish and tried it out this past weekend. The felt buffing attachment for the drill broke after about 30 seconds so I used a rotary polisher. It helped some, but I'll probably still replace the windshield.