Best way to understand is is here in their graphic.
Monuments were placed along border between US & Mexico long ago & Monument 1 sits on Federal land adjacent to private land. The strip of Federal land (easement) runs along border but is just a strip right of way. The Road is built on the private brickyard's property adjacent (which is denoted by the rocks along the property line). IBEW property ends at chainlink fence & is built on federal land, but terrain is rough & IBEW would have to build an access catwalk out to the monument on Federal land for the monument to be publicly accessible & they have never needed to because the brickyard was always happy to grant access on the road they built on their land in the past.
This is just the Dems & the ACLU flexing their muscles trying to subvert national security using union workers at the IBEW to violate national sovereignty on behalf of the Mexican Cartels who are apparently too lazy to climb to the top of the mountain & walk right across past where the wall ends. It is much easier to drive to the parking lot on the Mexico side, unload & walk a hundred feet through the brickyard's gate.