The courts can differentiate it by saying that the legislature has written implied consent laws that cover what you are deemed to have consented to when operating a motor vehicle, and that the legislature has not written implied consent laws for cell phones/etc.

Right now it's a pretty easy case for the courts, though higher courts have justified much worse with much less.

It's possible a legislature could write implied consent laws for cell phones, but I don't think they have yet. Not sure if they'd withstand court review, but I am afraid they might.