May I assume that the station was actually playing music on AM? Funny
thing, the original Mopar radio in my car had AM stereo. Back before I
replaced it (2001, cassette deck went dead), there were several stations
boadcasting in AM stereo, all of them talk or news. Perhaps there was
music on some of the foreign language stations, I didn't check them.
IIRC, the one station that was broadcasting music in English at that
time, was in mono.

Yes, it was C&W. Like most non-orchestral music, you're not going to miss the
uppermost octave very much.


In any event, I think clearly that the thing that killed AM stereo is [sic]
the lack of music being broadcast on AM by the time it became
available. Weather, traffic and Terror (TM) reports, are just fine in mono.

This is possible. There's also the fact that stereo FM had been around almost 20
years by the time stereo AM systems were approved. I also suspect converting a
transmitter to stereo AM is significantly more expensive than a stereo FM
conversion.

By the way, it's stereo AM, not AM stereo.