Okay, i went to Mod school and modded the game to remove tax income, therefore isolating trade income so I could run some experiments.
Here are some things I discovered.
As I expected, trade ships function the same way that Caravans do in Rise of Legends. They provide a constant stream of income regardless of where they are or what they're doing. So there is no insta-deposit when a trade ship hits a trade port. They serve as money factories just by being alive.
We already have a pretty good idea about how this income rate is determined. They provide .25/sec (rounded up to .3 in the infocard). The trade port itself gets a .075 bonus (rounded up to.1 in the infocard) for each node in the longest trade route (i dont' know whether this is technically divided amongst the 5 trade ships or not, it doesn't really matter).
What was news to me is that this Logest Route determines the value of all your trade ports throughout the galaxy. So even trade ports that aren't part of the longest route, or are in the same grav well as other trade ports get the benefits of this bonus. They just don't add to it.
Now for the interesting part:
When a trade ship is created it begins generating cash immediately. The number in the infocard hops up as soon as the trade ship appears on the map.
When a trade ship is destroyed, it CONTINUES generating income for a very long time. About as long as it takes to create a new tradeship. This is very important. This means killing a single trade ship will not affect the enemy's economy at all. If you kill two trade ships simultaneously, his economy will suffer the affect of being down 1 trade ship while the second is being constructed.
Basically what this means is it's virtually impossible to affect the enemies economy by attacking his trade ships. To have any noticable impact you'de have to be killing trade ships faster than they can be built, and you'de have to sustain this for a long time.
Trade ships have light armor and very few hit points. So fighters and scouts blow them up quite well. But consider that trade ships can and will be replaced by several trade ports simultaneously and there's pretty much no way to get ahead. Not that I can think of at least.
SO WHAT'S THE POINT OF TRADE SHIPS?!
Well since they can't be exploited to directly affect the enemy economy their relevance must lie in the microtransaction mechanic that's associated with them.
Every time you blow up a trade ship you get 50 credits. Not much, but when you think about how easy they are to pop, it adds up quite quickly. Later in the game, if you take 3 or 4 carriers filled with fighters, and park them in an backwater grav well and leave them to shoot down tradeships for a while, it will generate a fair amount of cash for you.
As far as I could tell there is no microtansaction penalty for having your own trade ships blown up. If he blows up your trade ship, he picks up 50 credits and you don't lose anything. I tested this by watching the pirates blow up my trade ships and seeing if my money counter went backwards. As far as I could tell it didn't, but I could be wrong if anybody wants to investigate this further I would be grateful. It doens't make sense to me, as a design decision, to have no penalty for getting trade ships blown up. That's how it worked in Rise of Legends, but in that game losing a single caravan did make a difference on your economy, and they got costly to replace, so continued harassment of them would start to cause problems.
So what's the purpose of trade ships? Well, it seems that if you build trade ports, you are taking a risk of providing your enemy with a small but easy source of cash that is relevant for a very tiny sliver of the mid-game. Early in the game, sending those 3 or 4 carriers out will be too much of an investment. And later in the game, the amount of money you'll get by popping tradeships will be a pittance compared to the amount you're generating by other means. So this risk only manifests itself for a brief portion of the game.
^That really doesn't seem like much.
The only other aspect that bears consideration is bounty. If blowing up tradeships will give you a significant cut of the bounty on that players head, then it could actually make them relevant, because the amount of money you get for blowing them up will scale with players' economies as the game progresses. In fact, if you got some major bounty from trade ships, it would actually thrust them into the limelight, making them a critical part of the bounty mechanic, and making the bounty mechanic more important in general.
But I don't know much about how bounty is distributed for kills. Do you get the same amount of bounty regardless of the shiptype? Or more bounty for bigger ships? Or do tradeships yeildeven more bounty? Which would explain why pirates like them so much. I couldn't test this because when i put bounty on the AI and then blew up his trade ships, I didn't get anything back. I think that's because you can only get bounty that other players put in, you can't get bounty back that you've put in. If ththat's the case, than for 1v1 this is still irrelevant.
Except the fact that losing tradeships doesn't hurt you directly means there's still something inelegant about the whole thing. Having a bounty on your head means other players will target your trade ships and make a little bit of money. So it's good news for everyone else, but not really bad news for you. It's just neutral news.
It makes trade ships more like another resource to be harvested, but the player who "owns" them doesn't really have a strong vested interest in them. (which is suppose is definitely novel and kind of interesting)
But my questions now:
Where can I find out how bounty distribution is calculated?
Is there really no direct penalty for letting your trade ships get blown up? He gets money and you lose nothing? Really? I find this extremely hard to believe, can somebody please verify this?
PS: While doing all this, one of the loading tips read "By destroying enemy tradeships..." But the game loaded so fast I couldn't finish reading it. This is the only official documentation of tradeships I've come across, so I'de really like to know what it said. Is there anyway to find a list of the loading tips and read them outside the game?