Two ideas of liberty in Mill ?
I agree that Mill is speaking of liberty but would argue that in OL ch. 3 his idea of liberty undergoes a change. Ch. 1 - 2 are about negative freedom - exemption from interference in thought and action within the limits of not harming others. Negative freedom protects us from external constraints. Individuality in ch. 3 is closer to what is normally called positive freedom. Mill is concerned with internal constraints that impede our development towards human excellence.
Automatons and individuality
The relevant passage of On Liberty (ch. 3) reads :
He who lets the world, or his own portion of it, choose his plan of life for him, has no need of any other faculty than the ape-like one of imitation. He who chooses his plan for himself, employs all his faculties. He must use observation to see, reasoning and judgment to foresee, activity to gather materials for decision, discrimination to decide, and when he has decided, firmness and self-control to hold to his deliberate decision. And these qualities he requires and exercises exactly in proportion as the part of his conduct which he determines according to his own judgment and feelings is a large one. It is possible that he might be guided in some good path, and kept out of harm's way, without any of these things. But what will be his comparative worth as a human being? It really is of importance, not only what men do, but also what manner of men they are that do it. Among the works of man, which human life is rightly employed in perfecting and beautifying, the first in importance surely is man himself. Supposing it were possible to get houses built, corn grown, battles fought, causes tried, and even churches erected and prayers said, by machinery—by automatons in human form — it would be a considerable loss to exchange for these automatons even the men and women who at present inhabit the more civilised parts of the world, and who assuredly are but starved specimens of what nature can and will produce. Human nature is not a machine to be built after a model, and set to do exactly the work prescribed for it, but a tree, which requires to grow and develop itself on all sides, according to the tendency of the inward forces which make it a living thing.
I think a more natural syntax would be : 'it would be a considerable loss to exchange even the men and women who at present inhabit the more civilised parts of the world for these automatons.'
Mill's thought is genuinely difficult to interpret here. Why not, as the questioner asks, 'the less civilized parts of the world' ? I think the key sentence is : 'Among the works of man, which human life is rightly employed in perfecting and beautifying, the first in importance surely is man himself.'
Humankind in the less civilized parts of the world is capable of developing 'on all sides'. It is important for Individuality that it should thus develop, and the introduction of automatons to do its work would harmfully hinder this development. It needs to learn and develop through activity and not have this activity done for it by automatons.
Now, it might appear that humankind in the more civilized parts of the world has already undergone a full development and so, if their work in a broad variety of tasks, can be replaced by - exchanged for - automatons, this would be a smart deal. Mill disagrees. Automatons work (so Mill understands robotry) exactly to a fixed pattern of activity prescribed for them. They do not experiment; they do nothing new, they do nothing old in a new way. But human beings precisely do or should experiment; the scope for experimentation would diminish with every task abandoned to automatons. Even in the more civilized parts of the world, humankind has achieved only a pale prefiguration of the Individuality of which it is capable. It would be a poor exchange to have automatons do the very tasks in experimenting in and with which human Individuality develops and is improved.
I take this to be the main sense of Mill's passage.
