Colo chain law applies to semis so that they don't get jacknifed and block the roads.
Unlike California, we don't mandate them for autos. Not sure why but perhaps it's because when the cars need chains the trucks have already jackknifed and closed the road so you can't go anyway....
The ski industry is dependent on keeping I-70 flowing so there are lots of resources applied to it.
On the other hand, trying to drive eastbound on a Sunday afternoon in ski season is a plan to spend a long time moving slowly on the road.