Who says you have to lie? You just don't need to incriminate yourself. They're the ones with whom the burden of proof lies upon. They bag hoardes of people at random when the aggregate traffic body is moving above the limit and the truthful response is "as fast as everyone else was" there.
I do see your point. However, just because everyone else is driving like a maniac is no reason that I follow the flow. Rather, I pull over to the "slow lane" and wonder where are the cops? This is especially true when I am going 65 and some yahoo passes me in the breakdown lane.