Maybe it was a ploy to have an excuse to charge more for whatever job that was associated with. Some poor unsuspecting customers won't ask, or assume the contractor is "taking care of them". Money brings out the worst in most people.
The gray box is a Pelco camera power supply, that most of them have a section boxed off in the bottom for the transformer, to seperate primary voltage from secondary. There is only a KO on the side to get the 110 in.
I am not sure what the box served. I did open it, and there is also a bottom KO in the same corner. There is also some additional space in the bottom 3", where it would have been possible to make your own KO.
Now, it IS possible that this was an incomplete installation; the "security" contractor was still working when I took this pic.