because journalist in Vietnam were documenting what armies do. People saw pictures and videos of human beings suffering. The saw villages being torched, they saw kids running with severe burns from Napalm, they saw dead bodies, people roped together. It was nothing out of the ordinary for a combat zone, but to a lot of the viewing audience, it sure didn't look like a John Wayne film. Sadly, and just like in any war, there were some atrocities committed by US Forces. Plus, people didn't understand how psychologically challenging Vietnam was for the GI's, and that certainly could have been a contributing factor in some of the bad things that happened. It wasn't like other regular conventional wars we fought. Our guys didn't know who or where the enemy was most of the time. Many didn't exactly understand what we were fighting for or what the objective was. The average age of a combat soldier in Nam was 19, in WWII it was 25. Just from brain development and wiring , a 25 year old can handle war better than a 19 year old. The people that mistreated the GI's just didn't understand, they made a mistake. All of their anger should have been directed at positions , and none of it at the GIs.