What do managers in England do differently from deciding who comes and goes?
They are in sole charge of it.
No case of having an influence or suggesting targets to someone else. Some managers even negotiate the transfer themselves, but the Man Chief Executive has been doing that for quite a while now, I think.
Being in charge of transfers also means that they will be in ultimate control of the club's scouting system and having to spend time trawling through scouting reports and all that sort of stuff.
Now, most British teams are gradually moving away from that to system more like what is in place in Italy, but I believe the system at Man Utd will have been pretty close to a classic British one for the most part.
Then again, it might not have been.
We don't really know any of what was going in within the club and are only taking educated guesses.