Because while they were occupied with me, they weren't chasing the other haulers who also got through so I even helped my teammates, in a space cow against FDLs
It doesn't make sense for that space cow to put themselves in a position to put up with a player in a FDL because, unless they just enjoy running away, the right choice is to not be in open. Your teammates' most valuable contribution is their time. They're picking an option where they can be forced to spend time running away instead of delivering cargo. That's the wrong choice. That's how the game is designed.
The only way they can get value for the time is to kill the attacker, but that's not possible. They can build a trade ship that can survive a fight with a combat ship; they're damn sure not killing the combat ship. This isn't pvp combat; it's pvp attack/escape. They win via escape. Failure costs the time spent getting the cargo and the credit value of the cargo. They've given merits to the enemy. They have to spend even more time in the boring travel mechanics to recover. If they win; they're still punished with more time in the boring travel mechanics. It's bad if they win and worse if they fail.
NPCs are different because the trade ship can fight them. They're balanced for it. Any half competent player can just opt out of combat and the NPC goes away. If they want to spend the time, they have a fair chance to 'win'. Success provides mats, rep and money. NPCs have value.
Winning attack/escape with a player is worse than not participating because the reward structure (kill the ship for a bounty) is not aligned with the design of the interaction. Their goal is to deliver stuff. They can deliver X tonnes per Y minutes. If Cmdr Richard is there to stop them, they can deliver the same X tonnes in Y+n minutes. Regardless of the outcome of the interaction, they're in an objectively worse position for having the interaction. Cmdr Richard has no value.
Open only doesn't change that. Having a wing with them doesn't change it. A player bounty board doesn't change it. In all cases, if your goal is anything other than having the interaction; winning the interaction is worse than not having the interaction. That's the issue. The design is fundamentally broken. You're being forced into an interaction where every possible outcome is negative.
I'd consider myself an end game player. I have billions. It would take 100 rebuys before I'd notice a change in my balance. I'm usually out of storage for mats. I can't remember the last time I've bought a ship and wasn't able to G5 everything before the first flight. I'm not worried about dying. I'm worried about spending time on a worthless interaction. Time is the main currency and I'm not running a charity. I'm not letting someone force me into an interaction where winning is worse than not having the interaction. They have to fix that. Don't add incentive or force people to participate in a broken mechanic. Make winning the interaction worth the time given to the interaction.
Mouse vs Cat vs Dog. Build mechanics where each has the chance to win. This isn't difficult; but if you don't want people to exploit it with an alt account, they'll have to add a penalty for attacking and failing to kill a target. Yes; it means that 'attackers' have consequence for failure. That isn't a bad thing. They can't treat players' time as a free resource.