I just thought an historic reference might help clarify that the incorrect use of indicators is apparently not Germanic in origin.
Indeed it might be inferred from this piece of historical poetry that the ultimate source of misuse could be both British and female
Lady Boadicea's chariot had scythes upon the wheels
That made the stoutest hearted Romans turn upon their heels
But the thing the Romans hated most, and that gave them such a fright
Was the way she put her left hand out, then charged off to the right.