I had a customer in today with Apple Mail problems, & when he went to shut down his Macbook (a newer one, Touchbar & all), Mail stopped it & flat-out refused to quit. My customer spent 5 MINUTES just getting the damn thing to turn off.
#Unix & #Linux: Can kill just about any kind of process & shuts down when you tell it to.
#Windows: Tasks can stop themselves from being ended, especially tasks not responding. But ending them to shut down? No problem, mate! Shutting dow--UPDATE TIEM!
#MacOS: "Hold my beer." (Gives you a spinning beachball.)