I believe that etiquette has diminished not only in golf, but in society as a whole. To the OP's comment, the coach should have handled his students and situation in a better way. New people need to to be educated, and educate themselves on how to compose themselves on the course. I'm relatively new to golf, and admittedly I made some mistakes that others (even complete strangers) made me aware of, and of which I was thankful for. Some people see this as an offensive action, but really its only for every golfers best interest. Its just not a matter of following formalities, but also a huge matter of safety.
The younger you can teach and educate someone, the more apt they will take that information with themselves for life.
What kills me is how many adults have no common sense whatsoever. And this is coming for a 23 year old.