[More on The Hobbit, for earlier discussion see here]
I knew there was stuff I was forgetting.
The Goblins under the mountain. Their economy runs on what? They have a lot of wood, theirs does not appear to be a woody mountain. to get to an exit near woods the dwarves had to first fall deep within Gollum's depths. The Goblin part of the mountain is rocky and without vegetation They are in communication with the Orcs outside of the mountain, do they trade with them? Are we to see them as... miners perhaps? The evil dwaves trading the riches under the mountain for food and construction materials?
And how does the entire evil economy work? If you're bad you're killed, I get that. But what happens if you're good at your job? What are your rewards? In order to be compensated you need to want something, but do we ever see goblins or orcs with much more than the clothes on their backs and weapons in their hands? Do we ever see them want much more than that? They don't seem to be after finery or gold or jewels or whatnot. What do the goblins do?
What do the orcs do when not hunting oakshield?
What do they want?
Consider all the goblins under the mountain, where did their food come from, how were they compensated for their work, what were their daily tasks? Were there so many bridges because they finished building and said, "What now?" to which the response was, "I don't know, I guess we just build more bridges"?
That's a huge population in a place with no evidence of food beyond mushrooms on the lower levels they do not seem to venture to. There can't be enough travelers falling into their traps to sustain them. There's no evidence that their aspirations are higher than their wooden home.
There was a bounty out, but what would the bounty be paid in? "Here's a tasty elf I killed," perhaps?
What the hell are these people doing when they're not encountering wayward travelers?
Some must be tailors, some must be smiths, some of the orcs presumably train the mounts. Perhaps some are cooks. Are some farmers?
We see armies, but no evidence of the infrastructures such armies need, and no evidence of the wanton destruction such armies need when they lack the infrastructure.
For four hundred years Middle Earth has been in a state of peace. So these armies of orcs and goblins cannot be living off their conquests because they're not making any. Yet they are so many.
What are they doing all of this time? Other than making kingdoms of wood inside of mountains, I mean.