The structure is changing, many distributions already are merging more and more of the duplicated subdirectories in /usr/ with the counterparts in / but it takes time to complete that and at the moment those subdirectories are often still there but as symlinks to be compatible with older software (and sysadmins).
Sounds like you want savapage https://www.savapage.org/
It by default runs on its own port but that is easy fixable with a reverse proxy.