Well, fluff, since you say you were making a theoretical question, and "was asking about the sociopolitical reasons behind existence of Zoners" and not discussing game mechanics, then my point about the server rules turns irrelevant. Luckly, Spazzy and Karst explained that on a more "inRP" way.
But I want to talk about the notion that Zoners are "off-house freelancers". There is a basic difference between a freelancer and a zoner: most freelancer live in a house, are house citizens, they just prefer to work for themselves or they cannot work for a corporation. Zoners decided to leave the houses, they are not house citizens, they don't care about the houses, they prefer the dangers of the outer-worlds than the corruption of the houses. And freelancers have all that bounty-hunter part that has nothing to do with Zoners.
And, speaking of the "neutral diplomacy" of the Zoners, anyone that runs around with that "you can't pirate me" attitude is a fool. It's very hard to be neutral. You end up in lots of "sticky" situations. Like trying to make Corsairs and Core not to clash right outside Freeport 11. But THAT'S the fun in it! The most enjoyable RP's I had on zoner chars were always walking that thin line between friend and enemy. Playing the double agent game and pretending to be friends with both sides of a conflict can give very fun RP.
Oh, and by the way, someone said "try to make zoners hostile to some house". Well, zoners were once red with gallia (not that anyone went there, but at that time we had to go there for the cryocubes) and OSI is stilll banned from Rheinland for a failure in that "double agent" game I was talking about.
