Bigfoot ground wires?

So are the 3 wires on the Bigfoot front drivers side tiedown ground wires? Since the camper doesn't have a frame to ground to I'm assuming that's what they are. But under what circumstances are they grounding? The camper would ground through the power cord while on the truck and the 30 amp cord while using campground hookups.
It's gotta be some simple reason I'm not seeing.