That's because they were omitted.
More likely is a map showing only the accessible areas of that level, with maybe a few areas showing fuel next to them.
point being, inaccessible areas waste time, paper, bandwidth and strain the resources of some smaller laptops on VTTs for no gain in functionality.
If a fuel level only has elevators or ladder shafts, there is no point in including them. If there is 20 (or 200) tons of access in a 1000 ton deck, map the area you can game in and link the access points to the maps above and below. Maybe you have structures similar to wings that spread out to twice or more the usable width. It contains nothing but fuel, processors and armor. Omit that and note it was omitted. It adds nothing.