The problem also could have been that 1.5' of snow may not have been much but they went down a hill and couldn't turn around and go back, or they got stuck in a valley and couldn't make it up. (I didn't read the article.)

In some places like here forest service roads have road signs and look like normal roads, but also are labeled on smaller signs the forest service digits.

I can see how this could happen very easily... GPS or not, if you are not familiar with an area and go down a road that is nearly impossible to get back out of you cuold be in trouble. My road is one of these roads, and with <1' of snow for almost all cars it would be impossible to get up some of the STEEP south facing switch backs, also with my pickup it's impossible to turn around due to how narrow the road gets when it snows, I have to find a driveway that's been cleared and then work it to turn around.

I think it's easy to judge the mistake and blame the GPS but I can very easily see how this could happen to even those w/out a GPS who make a wrong turn following bad directions and end up stranded.

W/out being there it's hard to say for sure everything behind it.