Well the lowerhive and the underhive are two very seperate sections of a hive city. Living in the underhive is much more of a madmax style existence compared to the labour class poverty of the lower hive. It doesn't have much in the way of businesses or establishments and no one same ever goes down there willingly. It's hard to overstate how destitute it really is compared to even the lower hive levels.

If it was easy to leave the underhive and just waltz into the lower hive there probably wouldn't be as many people living in the underhive.

I assumed my character would probably be contained in the underhive until her gang fought its way up to the higher levels