Shepherd's Pie

What is the deal with vegetarian recipes for shepherd's pie? I was looking for a basic recipe to work with, so I could make a kind of cottage pie, and found all these recipes for lentil and carrot "shepherd's pie." Evidently, there are some sheep made of lentils out there that shepherds are herding around.

Shepherd's pie is made of meat, lamb specifically, thus the shepherd in the name. Cottage pie is made of beef. I've heard of fisherman's pie made of fish, maybe there is a poulterer's pie somewhere, and now we can have greengrocer's pie.