Someone working on the job, like a taxi, driving a truck, or even in the office, listening to music is not going to be in violation - unless the music were played as part of entertainment for customers/patrons.
The cop will unlikely be found to be in violation.
The person filming in uploading, that production would probably be in violation under the 'Transmission Clause'.
Taxi drivers do have to pay license fees in some countries.
> or even in the office
According to the RIAA, you need to license music in order to play it in the office.
That being said, I would say they're probably right, because it doesn't seem that different from a store or restaurant playing music.
Even to the extent workplace semi-public (for coworkers, not primarily for public customers) entertainment use might be fair use [0], use by a state officer for the purpose of leveraging known provider policies to inhibit First Amendment protected public monitoring and distribution of recordings of police activity would seem unlikely to be viewed by a court as fair use (whose statutory definition was crafted to follow the parameters of a judicially-articulated restriction on copyright that itself was viewed aa necessary to conform copyright to the First Amendment.)
[0] a quite controversial position itself.
Generally speaking, "public performance" means outside a small social group consisting of friends and/or family.