We rent cars and drive them. Very rarely have I driven a SUV. In my experience, the SUVs in rental fleets are not better (from a traction standpoint) than a minivan or sedan and they cost substantially more with less functional cargo space.
I don't think anyone here claimed that the rental fleets are equipped with appropriate tires.
However, changing Colorado's laws could at least nudge the rental fleets into the right direction, as they have more incentive than individual drivers do. One could imagine rental companies being required to post notices about these restrictions.