Hollywood has been doing that since the 60's. Very few, if any, current Hollywood types ever served in any military. So they wouldn't know reality if it fell on 'em. Certainly not Fox or Penn.
Very few movies made with Brit or Canadianicon military portrayed.
"...fair reflection of what the average American soldier..." No. Isn't a conscripted army any more. All volunteer since 1973.
Casualties of War was another American anti-Viet Nam/anti-war fairy tale movie.