Not that I want to perpetuate an argument about head shells, but I always thought Reed and Schroeder tone arms are in a group that have non-detachable head shells. At least that applies to my own Reed tonearm, and any Schroeder tonearm I have ever seen in person. And your list is largely a chronological one. There was a time in pre-CD history when every tone arm had a detachable headshell, except maybe the Triplanar (late 1980s) might have been the first to have a non-detachable head shell. Since the turn of this century, there are many newer tone arms that have non-detachable head shells. That anti-feature seems more likely in the most expensive examples, oddly enough. Not that I care either way.
I think what you see on the Schroeder, the single screw, allows for adjustment of headshell offset angle, not for headshell removal. Same for Reed.