This concept, and flaws, need to be distinguished in drivers ed, and commonly reminded: A “Share The Road” sign may give the motorist behind the cyclist the wrong message that the motorist can choose to share, or not, since the implication is that the bigger car has bigger rights that supercedes the right of the cyclist.  It may also give the motorist the wrong impression that the LANE can be “Shared” with the bicycle – i.e., that they can co-exist side by side in the same lane.