I dunno. It may have something to do with the fact that many people wire them up directly to the power circuit, especially in older houses. I've included outlet

I dunno. It may have something to do with the fact that many people wire them up directly to the power circuit, especially in older houses. I've included outlets on GFCI circuits for the kitchens I've built, and seen others built the same way: those situations call for a normal power cord with a plug.