By will alone I set my mod in motion (Dune mod ideas)

[Suicide Junkie]

Warppoints could merely represent a fixed trading route for guild ships. If you stop paying the guild, they will close the warppoint.

With that kind of theory, the houses would be able to move thier own ships and units where they want, and the Guild simply counts them and sends the bill.

Imagine having a guild ship going back and forth through the warppoint between the systems every SE4 day.