Time to reassess this. If you are going uphill on ice, your indicated speed (speedometer) may be less than the actual vehicle speed if there is a loss of traction.
Going down hill on an icy road, the one way to guarantee loss of control is to hit the brakes. You are often better off to let engine compression slow you as well as it will and stay off the binders.
If the tattle tale isn't telling the whole story (terrain, etc.) then it bears false witness.
ABS systems sense when tires/wheels are locked up and the vehicle is still in motion.That is how they work. Some newer cars sense the traction gained at an given moment and transfer power to tires/wheels that register the best "grip" at that moment. This information would be recorded along with the rest. As for spinning tires going uphill, while I cannot name a current system in use, I would offer that a similar system could be employed to monitor such happenings.