Parts books make poor reference guides for any restoration. Even to this very day, parts books(and in todays world-computers) got revised mid year several times. There were omissions, superceded parts, part number revisions, vendor changes, and on and on. Additionally, period road tests often feature cars that are "pre-production" cars that quite frequently have incorrect parts and/or differ somewhat from what you would normally see on a run of the mill regularly ordered vehicle in the middle of the production run.
Putting the photographic evidence and authorized factory engineering drawings aside- I find it hard to imagine that every single '71 stripe delete Challenger had owners who put R/T badges on their cars. It's just doesn't seem likely. I would think it would be more likely that the ones that people remember not having them were factory mix ups that should have got them but didn't, or they were removed by thieves or simply just fell off. It was a very common practice in those days(theft of badges, logos and hood ornaments).
And for the record Jeff from CT, you are entitled to your opinion and right to believe otherwise and I respect that.
MB