Some stations got the audio and video via landline. The video was delivered via the A2A system:
https://www.americanradiohistory.com...l-1955-4.o.pdf
It was easy to add a second audio channel.
But for microwave fed stations, it required an additional subcarrier modulator at the microwave transmitter and an additional demodulator at the microwave receiver.
So it cost a little more for them.