I saw your hose-and-buggy sign from Ohio.  We have those signs
here as well, since I live in "Amish Country", PA.  And the
horse-and-buggies are quite common.  They share the road with motor vehicles even on state roads, but stay on the shoulder when possible.   And I think it's legal to pass them on a double line.  Naturally, it's unwise to pass them going around a curve.  And I have to admit that finding them on a curve can be annoying, particularly when you're running late.  I don't represent the group, but if I might put in a "plug", information about the Amish and Pennsylvania Dutch can be found at www.padutch.com