Hmmmm, an interloper . . . . .
We operate with the GMC frequencies part cross-coupled, vehicles hear acft but not vice-versa, but the AIR frequencies fully cross-coupled so everyone hears everything that's going on around the runway.
The trouble with the former is that if a tug is passing some towing request he can get stepped on by an acft. You deal with the acft and then have to ask the tug to say again. This just adds to the RT time and work load. Some of us would like GMC fully cross-coupled.