weastcoastProbably because your edges are way too sharp for it. The steel will shred that plastic up all day long and you may have some nasty edge catches as well.
Try dulling your edges down (underfoot only) with a bigger file or a gummy stone. Should do the trick.
This. De-tune your underfoot which is the part of the ski that your feet and bindings are on with either a diamond tuning file or a gummy stone. At a 45-degree angle go back and forth so that you're rounding the edges of your ski to the point where when you run your finger against the edge you notice it is much smoother when compared to the tip and tails of your skis. Make sure to start from the top and work your way down. You do need to put down some pressure and go back and forth pretty fast in order to give it a nice de-tune so don't really worry too much about overdoing it. You'll definitely notice a big difference.