Star ship berths

Khs has a dice mechanic for figuring how soon a berth becomes available, yet one of the rewards of Dramune Run is a ships berth paid up for three months at inner reach. It seems odd to me that something so in demand could be tied up and left empty becuase someone paid rent but is off Galavanting around the frontier with their ship. Or does it simply suggest that political and piratical situation in Dramune that small ship operations can aford the going rate to rent a berth.