A manager can control what is done under them, but if one of their teams/members needs something done by another team they have no control.
Their manager might control the manager of the other team though, so the decision goes up the line until it hits someone who has both sides of a problem under them and can make the decisions on priorities/cost etc of the requested action.
In small companies, this may just be one or two layers, but in bigger companies it becomes a disfunctional disaster.
For a real answer:
A manager can control what is done under them, but if one of their teams/members needs something done by another team they have no control.
Their manager might control the manager of the other team though, so the decision goes up the line until it hits someone who has both sides of a problem under them and can make the decisions on priorities/cost etc of the requested action.
In small companies, this may just be one or two layers, but in bigger companies it becomes a disfunctional disaster.