IMHO that is a fair question - why in major snow events like this are they not being pulled off the road?
This doesn't happen that often. Inflexible businesses that refuse to plan accordingly shouldn't supersede safety - this happens every storm on the same predictable stretches of 400 series highways. 
Yes I realize car drivers can be atrocious in these conditions but the accidents tend to be minor - people walk away - it's the truck wrecks that get the headlines for a reason.