I saw this phrase while I was reading an example of the usage of an adjective on Cambridge dictionary online i.e. included. This is the provided link: included. The complete sentence is:
The trip cost a total of £250, insurance included.
Why is it not:
The trip cost a total of £250, insurance is included.
Again, another example:
The fee covers everything, babysitter included.
Why again is it not:
The fee covers everything, babysitter is included.
Insurance and babysitter are nouns and included is an adjective, so why is this allowed? What I'm familiar with is adjective+noun and I've never seen noun+adjective before.