Yes, they may have been going a bit fast even when the snow was already on the ground.
OTOH, you cannot simply slow to a Crawl lest you get plowed from behind. Again, low visibility…what are you going to do? Maybe drive off to the shoulder and wait….but still get clear of the car.
There was only one lane open on the highway and it was clear you could not see far. One lane means you are also likely on ice, yourself, if the other lanes are covered.
You go slow and occasionally tap your brakes as you move forward. Ideally, you pull off if you are concerned, but you don’t plow forward at 70 MOH with a full load and not seeing far, while driving on a known icy interstate.
This is not rocket science for anyone from the area, but those on an Interstate are most likely to be from other places.
These people were stupid, especially for the ones who know what to do, and didn’t.