Why don't fictional characters say "goodbye" when they hang up a phone?
Apparently in the film industry, goodbyes are considered inefficient.
According to screenwriter Josh Olson, "It's possible that some filmmakers think it slows down the action if characters say things like, hello, goodbye and 'Sorry, I have to commandeer your car for the sake of homeland security.'"
Many filmmakers believe that although it’s natural to end a real-life call with “goodbye,” in a movie, it’s awkward and a waste of precious screen time.
Probably for the same reason they never thank waiters who tell them they have a call or actually bring the phone to the table for them. Or the same reason that they feel that it's perfectly OK to drive like maniacs, endangering all about them. And that's not just cops and robbers, it happens constantly in comedies, romances, movies/tv shows of all sorts. SO many characters in these things are completely self absorbed, maybe the writers thinks it gives their problems gravitas.