Are we meant to assume the rebel worker bots on Mars are humanoid merely as a personnel interface aid, while underneath not being truly sentient, thus getting around the oft-mentioned "we dislike slavery" canon violation?
Seems to me that there are two possible interpretations of that scene from "Maps and Legends." Either:
1) The androids on Mars in 2385 were not sentient, and the HoloDoc's crusade for the rights of sentient holograms begun in 2377 was successful by 2385; sentient holograms were not used for non-consensual labor; or,
2) The androids on Mars in 2385
were sentient or were in the process of becoming sentient, and the HoloDoc's fight for sentient holograms' rights was still ongoing as of 2385.
If that were the case perhaps the EMH looking mining holos are a stripped-down version of the software as well.
I mean, those EMH M1s at the end of "Author, Author" must have been sentient, because non-sentient programs would not be interested in the political message behind
Photons Be Free they way they were.
According to the tie-in novel The Last Best Hope (written in consultation with the showrunners and thus presumably consistent with their intentions), the Utopia Planitia synths were indeed non-sentient. The Federation still hadn't cracked Soong's secret to creating sentient positronic androids, which is why Maddox was pursuing fractal neuronic cloning in hopes of getting around that problem (and that part is from canon).
I would probably go with Option 1 then.
As for EMHs, it was always a given that they're normally nonsentient. Voyager's Doctor developed sentience because he was kept running indefinitely in a situation that challenged him to learn and grow, and because Kes and eventually the rest of the crew encouraged him to develop as a person. Presumably none of that is true for most EMHs.
I don't know that I agree. As I recall, the EMHes basically worked by copying a humanoid brain's engrams and combining those with a medical database; that and the fact that EMHes are apparently capable of creative problem-solving and subjective data interpretation from the first time they're activated, to me strongly suggests that EMHes are inherently sentient and the Federation didn't recognize that because the idea a machine they built could become sentient is a cultural blind spot.
(And I just ignore that whole "mining holos" tag because not one thing about it makes any damn sense. Surely they have mining machines or phaser drills that are a million times more efficient than bloomin' holodocs with pickaxes.)
Maybe there's some inherent property of dilithium that prevents automated mining at a macro scale and requires the presence of an intelligent mind to determine how to mine it at micro scale. That might have the virtue of explaining why there had to be entire mining
colonies full of miners in "The Devil in the Dark" and "Mudd's Women."
Of course, Trek has yet to address the obvious contradiction here. Given that we have seen holographic AIs achieve sentience on multiple occasions, and given that the hologram part is just a physical interface for a disembodied AI existing in a computer somewhere... why not just stick that computer inside an android body? Why should it need a positronic brain? If the Doctor's program can fit in the mobile emitter, it could easily fit inside an android's skull.
I think the goal with a positronic brain is that the creator wants that brain to become sentient and develop its own personality independent of any pre-existing humanoid brains, the way real humanoid children do; whereas EMHes achieve sentience by virtue of being essentially enhanced copies of existing humanoid brains. Hence why the HoloDoc and Lewis Zimmerman had identical personalities: the HoloDoc was literally a copy of Zimmerman. (Presumably, somewhere out there, there's a Dr. Andy Dick that the EMH Mk II was a copy of.) Whereas Data, Lore, and B4 are many things, but none of their minds were copies of Noonien Soong. And, similarly, none of the androids we saw on Coppelius were mere copies of Data or of Alton Soong or Bruce Maddux.