I have a plastic scraper i've been using for a few years with several different cars (an 02 focus and 99 explorer) with no issues. Its a fairly soft plastic, I don't see how it could possibly scratch the glass as badly as mine is unless the glass was just junk to begin with. I think I've only had to scrape my windshield once this year (every other time the defrost handled it well enough), and that was about 2 weeks ago. I only noticed the scratches a few days ago. Still, plastic should never be able to scratch glass so I'm fairly certain that isn't the cause.
I did find that my deductible is $500 (I should probably know this...), and Safelite wants about $350 for new glass. I'll just drive with my scratched glass until I can't stand it or the scratches turn into cracks.