The point of this post was to alert visitors (and most who come to BC during the winter are probably coming for skiing i.e., Whistler for most) to the pitfalls of renting a vehicle where the vehicle may be "winterised" but almost likely not to have qualifying winter tires (99.99% likelihood in B.C., almost 100% likelihood in Seattle).
We usually rent a 4WD to go up to the interior (for family, not recreational, purposes) for the x'mas hols but ended up booking flights (as we did last year). Good thing as we weren't aware of this requirement until the past few days. Last thing we want is to get into an accident, even if no fault of ours, and not have insurance coverage because of not having winter tires. We've just been lucky so far that whenever we've had cars, the highway has been clear, or wet/mildly slushy at best, and when we've had 4WD, the roads have been reasonable (but completely covered by compacted snow for long stretches - clearing to the pavement seems to be a foreign concept for the privatised alleged-ploughing crews (the ploughs just compact snow, not scrape it off the pavement, and the smallest rock that's used on the Coquihalla and connector seem to be much larger than pea gravel size -using sand is a foreign concept). I'm well aware of the 4WD vehicles' traction/stability limits while it appears a lot of 4WD/SUV drivers aren't given how many you see off the roads (and not even just on curves).