I was pumping gas and the gas pump decided it should advertise at me and clue me in on the latest celebrity gossip. We really have no concept that we shouldn't degrade the public realm.
Bring expanding spray foam with you and fill in the speaker grille and muffle or mute the sound. Other people will greatly appreciate it and the employees most likely won't care until it comes time for inspection from corporate or state agencies. I've seen it more than once at Speedway stations.
In that case I think it’s perfectly acceptable to degrade the speaker and screen that were placed in the public realm.