Telling people you're doing something, but giving them no other options, isn't good enough.
There are roads near me which do "toll by mail" where they snap a picture of your license plate, and then bill you the toll even if you don't have EZ-Pass. There are signs which announce this, but unless you're planning to drive 90 minutes out of your way, those sections of highway aren't avoidable.
Even if there are other viable options, the average citizen doesn't really understand the implication of losing their privacy, so they can't make an educated decision about whether to give it up. A simple sign doesn't solve that fundamental problem.
Sure, it's a step in the right direction, but you said "I'd be content with...", i.e. you're content with stopping there, which isn't nearly a good enough spot to stop.
So in the end people who don't want to be tracked in their movement by the government only have the option to drive through small back-in-the-woods roads, while the new "highway toll" is to have your data harvested?