5.6 Fleeing from combat and then docking at a station or planet while you are in range of the ship you were fighting counts as PVP death. Transports and freighters are exempt from this rule.
Previously, it wasn't possible to attack transports in cruisers and battleships, and transports didn't have to leave the system when killed.
This line was added at the same time those two were changed, to balance it out I guess.
Also, transports might not be docking because they are fleeing, but simply to buy/sell goods.
It seems kinda lame that a pirate that can't actually kill a transport will "kill" it if the transport just ignores the pirate, continues its route and then docks.
Basically, like jammi said, if a transport reaches a base, the pirate failed to stop them and the transport "won".
Rawr. I'm lazy to post screens and report guys who f1'd out of piracy and you think anyone will record movies to prove that the docked cargo ship wasn't trading at all?
A trade ship escorted by two fighters can be dealt with by a gunny, which then with ease takes remaining escorts.
If the snubs strike the convoy, they have or-or - either they rethreat and survive, or kill the transport and then have low chances against it's escorts (which have still full b/b, while raiders don't).
Balance is the problem. Deal with the balance first, and everything will be fine.
By these stupid rules leading team is trying to solve problems in VERY unnatural way.