It's polite to use somebody's name when talking to them
Ian is a front liner supervisor at work and has trouble remembering names, and needs to ask his employee Frank to go do something.
Ian needs to get Frank's attention.
Ian quickly glances at Frank's name tag in order to remember Frank's name before calling for him by name.
Ian shouts hey you to get Frank's attention, and repeats the phrase until Frank looks up at him.
Frank stops what he was currently working on and does what Ian asks him to do.
Frank thinks Ian's pretty rude for not calling him by name, and mentions so to Ian's supervisor.