Totally guessing here, but I see problems with that...Has any ski area ever tried laying down that British plastic ski mat stuff and then put snow on top of that? Seems like covering the slope with a year round skiable surface would be ideal plus it doesn't form ruts. Why isn't it more popular?
1) Snow not adhering in any way to the plastic like it does grass/earth/rocks and sliding off
2) The plastic not being as cold as the ground and not preserving the snowpack as well
3) It would still only cover a small portion of slopes
And there are a few of those in the US... 3 at least in Minnesota, Virginia, and Connecticut. They are small and presumably aren't that popular, or there would be more. I'm not sure why they're so much more popular in the UK - maybe because they get less snow?