I'm no expert but I'd think that a train like this would be a big target for terrorists and would require a similar level of security to airports. You wouldn't believe the security issues going on right now in the county with the Dillion Dam.
I'd think that more throughput on I70 would mean more front rangers which destination skiers (who spend money) strongly dislike.
They're lucky that their cities and transportation systems weren't designed in the automobile age.
Destination skiers would love to have an easy transportation option out of Denver instead of having to rent a car or deal with shuttles. The easier you make it for people, the more money they'll spend.
And really, the effectiveness of the rail system in Europe has nothing to do with when their cities/transportation systems were designed. It has to do with their commitment to providing a vital service to the public. European countries are constantly upgrading and improving public transportation. Riding an Amtrak train is liking taking a trip back in time (and by no means in a good way). I used to ride Amtrak a lot and I never once rode a train that arrived on time.