Expansion Bay for vehicle

Expansion bays on vehicles can contain: some lab or workshop or seats for 8 medium creatures or store cargo (50 bulk and 6-foot cube). 6-foot cube? I know that it is better not to search for logic in rpgs, but 8 sitting people in 6-foot cube? Is it another mistake in armory or I don't understand something?

I imagine that is loosely considered not to be exactly 6-foot cubed for the whole bay. But that the bay once converted has space for 50 bulk/6-cubic feet of stuff, while still offering enough room for people to move around as would be needed. Same with seating for eight. Eight fully equipped seats (belts, emergency things that drop from the ceiling, etc.) with room for rows and aisles that can be easily maneuvered in case of an emergency (maybe two people wide?). They're not packed like sardines.