I don't think that's the case if someone says, as they should, that the equipment conveys. A setup like this looks like it can take up to four different sources and that those sources can be selected, with volume control, from any room that has a controller in the home... AS LONG AS THE BASE STATION IS THERE.
Which it isn't, and that completely screws absolutely everything up.
I understand about what 'conveys' and what doesn't, but why would someone take half a system with them, rendering the half they left behind useless, and the part they brought with them useless? Know why? Because people are just stupid.
I left a full on 16x16 audio switching setup at my last home with keypads and amplifiers and an equipment rack with the gear in it. How the heck else would stuff work if that wasn't in place?