True... and I think it is pretty standard even today for people to be given enlisted clothing if rescued with no other items (and will be staying aboard for an extended period). As I recall, in Voyage to the Bottom of the Sea (1961) the Seaview finds someone on the ice and gives him enlisted personnel clothing.Well, that must be the way it was done in the U.S. Navy in the '60s, since TOS mirrored real-world military practice so closely.![]()
In the case of Charlie, this was a boy found stranded on a planet after many years, so almost everything he was wearing was most likely given to him by the crew of the Antares (who were still all wearing the old style uniforms).
In the case of Captain Christopher, I would guess that they were attempting to honor his actual rank more than anything else (which is why he was given a uniform with lieutenant's stripes). They thought they were going to have to bring him back with them and were already considering how to integrate him into the future.
The biggest problem in TOS is that the closest thing to enlisted clothing was the coveralls, which most likely seems odd to have guest stars wearing.
There were a lot of places where TOS got things wrong, but I think this is an example of just trying too hard to look for errors. Most of the OP examples are easily explained and don't seem to point to a systemic problem with the series.