Operating on the lowest bands in some circumstances it could be hard to keep all of the antenna within the AZ (e.g. top-band λ/4 chucked over a cliff.)
I think that is debatable.
For remotes, in contrast, the definition is perhaps more tractable. If you transmit with a remote it is under the authority of your transmitting licence. The transmitter is your station in the (UK&CD at least) licence sense, even if in ownership terms it is not yours. We can therefore say there is no 3rd-party station involved in the QSO. This distinguishes remote operation from operation through repeaters or gateways.
But no licence is required nowadays for receive (is this true in all administrations?) so we cannot use this convenient definition for the RX-only case.