At least in the US, last I knew, the ILS beams are not protected except in IMC, or by request.
Stockton, Calif, was a favorite for autolands by McDouglas, although they had a disturbance of the LOC once in awhile. Finally one day, they correlated the disturbance with a large truck on the road just beyond the airport, as it passed by the back side of the airport's localizer antenna.
GB