Here is a link to the US, where things are a bit different, but this illustrates another example of a perennial issue at the root of bloated costs: the lack of a profit motive. If units (in this case a law School) are not held to account for their profits, then the institutional pressure to maximise the resources they control is unconstrained. It is sheer benefit to the Law School to have another tenured post and nonsensical to turn a post down when it is available. In the UK it is a little different, but not very: posts are not tenured as such but they tend to be permanent all the same. Other resources, such as space, IT equipment or library holdings may not even be carried on the budget of the unit that uses them.
In the UK context, most academic units will at least be under pressure to break even, although it is rare to set more demanding targets than that. Non-academic units simply have to operate within agreed budgets, so if you can get agreement to increase your budget, why wouldn't you?
Now, of course, giving profit targets (and incentives to exceed them) to middle managers in universities would clearly create some risks and issues itself, so this post isn't a call for action so much as a comment that preserving certain cultures and practices has consequences.