It takes time for people to like a song. Maybe with well known acts it happens quickly - like the new Taylor Swift tracks. But having recently heard a local singer songwriter trying to play to a local audience they just didn't connect even though I know they have a good following elsewhere. So when Notes plays Mustang Sally he's cashing in on years of airplay and the audience hear the song they know they like. I played in a 60s cover band for years and we knew the audience liked the songs we were playing. And we liked them too so it was no hardship- we had fun. Playing covers gives you a headstart in pleasing the audience. And don't forget the Beatles started out playing covers.