Why Zoners can freely access houses?

[Cellulanus]

We Zoners need supplies.... Like every faction the zoners are not totally self sefficiant (or however that's spelt)
We need stuff....like fuel for instance

I can see Zoners going to the edge house systems for supply's to bring back to a freeport, infact the NPCs even do it (Zoner traders can be seen in Hamburg) But what reason would a zoner have to go to a house capitol to pick up supplys headed for another house system, completely ignoring the Freeports?

Sadly of course, there may be trade rout limitations for this, and when it comes to trade its irrational to expect people to trump profit for RP, but I'm sure it is possible to find at least one profitable rout that goes to a Freeport and doesn't require you to head to a house capitol for other than passing by.