LOTR goes into enough detail about Orc society about as much as knowing the tax policy of Aragorn as King of Gondor.
But even then, this analogy falls apart immediately. The uruk-hai were designer soldiers that were the best troops in the army because, you know, they were designed to be the best class of troops.
I do not know of any details in LOTR that goes into the promotion policies of the officers of Sarumans military.
Insofar as there is any hierarchy in among the orcs, it must have come from certain individuals showing themselves to be more capable, brutal, commandeering, or whatever else, than others.
I have not read LOTR and got about 10 pages into the Silmarillion before giving up, but my understanding is that Tolkien designed his world meticulously. If he didn't go into detail on this matter I have to assume that it was for a purpose, possibly either of avoiding unfortunate implications by comparison or of enhancing the dehumanized characterization of the, er, foreign hordes.
Outside of the fandom, LOTR is commonly understood to be problematic in its treatment of "race" and social structure, at least wrt contemporary society and its necessities for peace, order, and dignity. I don't know that this is a controversial take at all.
But even then, this analogy falls apart immediately. The uruk-hai were designer soldiers that were the best troops in the army because, you know, they were designed to be the best class of troops.
I do not know of any details in LOTR that goes into the promotion policies of the officers of Sarumans military.