Dangerous bandits.
Uku is peculiar; a high-tech world with a serious bandit problem. The government is bureaucratic and inefficent, allowing raiders to operate out of the wastelands surrounding the small number of heavily defended cities. Local police and security forces are hopelessly corrupt, and usually in the pay of one or more of these bandit bands. This collusion extends, unusually, into the starport itself, and the normally fairly safe high- and down-ports are quite dangerous places, especially if you appear well-to-do.
Anyone wishing to travel or trade between cities, or to land or lift a cargo from space, has to hire offworld mercenaries in order to stand a chance of survival. As a result, TAS has rated Uku a Yellow zone.