If Johnny is going down the road at 50 MPH, it is generally understood that he is moving relative to the Earth. Does this not establish the Earth as the preferred frame of reference? Since the preferred frame of reference is established ONLY for this particular discussion, it would seem to be a LOCAL Frame of Reference.

Semantics aside, I think we establish local frames of reference in many discussions. Does not the Earth go around the Sun? Does this not make the Sun the LOCAL preferred Frame of Reference?