I’m talking out of my ass here, but having worked on naval-adjacent projects as an electrician, we were asked to ignore vast aspects of our code for the sake of space. One project that we ended up selling off to another contractor was a refueling building for a sub, where all the utilities had to be ran in the walls, which required drastic under sizing of all of our conduits, sometimes to a dangerous degree.

Was none of this shit inspected

clearly!

Have you considered that smaller pipes are slightly cheaper, leaving more margin for profit?

If I recall correctly, this isn't some surprise either. The (lack of) sewage management has been a known problem through most(?) of its construction.

Ah the rare reversal of "the front fell off"