Really? NCR troopers care about and want to better the lives of fiends, great khans, viper gangs, etc etc? Those are people of the wasteland.
Anyone who expresses a willingness to better their lives is included, so yes. I can't recall Fiends doing that. Without knowing the Courier, they shoot at her, no chance for conversation at all. "Hi, hello, I was just passing by, how you doin?" If a group of people have gone psychotic and won't even talk, how can they be helped? Same with Viper Gangs. I can't tell you how often I wished that someone would just let me walk by their camp without shooting at me. I wasn't being aggressive to them or bothering them at all. So ok, maybe they're nuts too? Since it's a game, I can imagine just rounding up these groups and disarming them and getting them treatment but the writers didn't write it that way.
My knowledge of the Khans is only from FNV so I can't discuss their earlier FO experiences but I can see a willingness to improve their lot with the younger members coming up. Papa Khan has an understandable bitterness that he can't get past but Regis is willing to ally with NCR for the greater good. Jack and Diane are willing to make medicinal chems once Jack is taught how to make them. This is a good sign for them. My Courier arranges things so they have the best ending possible for them in the game. They all live and move on to better things. It's the only time I gain Infamy in the game. I don't believe the NCR are sainted but they aren't satan either. It was the best possible choice for my Courier.