Jinx, an example of being ganked that you seem blissfully unaware of.
i hopped ingame today for about an hour and was merrily pirating in S13. Lo and behold, a Rheinland Cruiser (police tag:angry2:) hops in and starts firing at me without a word. He's firing all cerbs and even a falcata with a bad pilot (me) can avoid him all day. So I did. and then a Corsair Huntress shows up. (Corsair ID/Tag). Do the capships shoot at each other? NO!!! They BOTH fire at me!
So then a trader shows up and I still try to pirate him. he jumps to NB and I follow...and what do I meet? A Bounty Hunter Battleship. So after blowing up the trader who refuses to pay (yep, I followed the rules while UNDER FIRE FROM 3 CAPSHIPS) I withdraw back to S13 to find 2 OC dessies. Which was really good for me cause I was out of bats/bots. Together we blew up the cruisers, and up to this point only the BHG had said something. the RH cruiser never said anything at all.
Now, the RP reason for the capships coming is; the houses and BHG are their enemies, so when these vessels come to kill their friends, they want to A) defend their friends and B) engage the capships far away from reinforcements/defenses.