Player Vs Environment. A series of Game Mechanics. From an IC-POW, here is no logic behind it, there is no explanation or idea that will suffice to hand-wave it.
There are several problems, I'll high-light 3 just to serve as examples.
1. The seemingly endless resources.
How many tons of materials do any single Empire, let alone the pirate factions produce on a daily basis?
The average price, in Tritanium, needed to build your average battleship is 7 million units. Let's ignore all other materials needed for now and go with this. A well-skilled player in a T2 fitted, bonus'ed Hulk using specialized implants still use hours to mine the Veldspar needed to aquire 7 million units of Tritanium, even with perfect refining and no tax. On any given day in the MMORPG EVE-Online, thousands of NPC Battleships are blown up in high-sec alone, let alone ratted in low-sec and null-space. How many thousands of NPC Hulks are needed to mine how long to keep up with that strain, ignoring for now the need to build new Battlecruisers, Cruisers, Destroyers and Frigates?
Let's go with infinite resources and near non-existent build times for now.
2. The endless supply of new crew.
Let's go with any of the ideas presented so far to explain this one. Or just say that any Empire or Pirate faction mass-produce legions of clones from well-trained crew well-versed in their individual jobs and that this is 'installed' into the clones as theoretical skills upon birth as fully grown adult Humans, and that within days hours of development, they are crewing yet another finished vessel from the endless resources and non-existent production times.
You now have an endless source or ships and personell to man them. What to do with it?
3. The endless stupidity.
This is the biggest problem of them all IMHO. The Pirate factions and the Empires never seem to learn. Endless waves of NPC vessels are daily out doing whatever it is your agent(s) want you to stop, or endlessly patrolling the resources they never seem to bother touching, using the same technology, fleet compositions, tactics and strategy. They never learn. Despite the inevitable result being utter failure and destruction of their assets in nearly 100% of all cases, no alteration of tactics, no change of strategy, no variation in possible actions are observed.
Even the most stubborn commander *will* alter his or her strategy when confronted by the very same result every single time, no matter how expendable and endlessly repacable your assets are. There is no logical or even remotely reasonable way to explain why places like Dodixie and any other missioning 'hub' is assaulted every day using the very same means as the day before, with the same predictable results.
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These are but a few of the reasons why, for us as Role-Players, trying to have our characters (who we pretend lives in a real universe comprised of Humans, Nations and their realistic behaviour and interaction with each other) go in detail about what is at it's core a few very unrealistic but needed Game Mechanics is a horrible idea. It punches huge holes in immersion and shows the game's limitations for all to see. Ratting, missioning, un-depletable resources and so on, it can't be detailed in any IC conversation or context, because it forces us to try to explain utterly unrealistic things in an IC manner.
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I'm hoping this won't come off as too YDIW, but I'll have to leave this here anyway - frankly, none of my toons will ever buy any kind of far-fetched explanation for the above factors, and I *will* try my best to smooth over any of these things if anything like it comes up IC. I honestly think it's for the best that we don't try to explain this away, because in the interest of good RP and immersion, we can't.