How did this situation develop?
The building went up in the 60s, when the strata world was young and builders who had only ever constructed two-story houses (if even that) were suddenly building low-rise apartment blocks. Regulations were scant and easily ignored. We used to own an apartment of similar vintage where the bath and sink overflow was a shallow channel across a section of the bathroom floor to a pipe that dripped water on to the path below. As far as I know, it’s still there.