I think this is pretty much the standard practice for any department in almost any business/organisation. It's just plainly to show that the department does use the money, and requires the money budgeted towards it. Thus, if they don't use all that money, they demonstrate they require less budget for the following term. Similarly, if they demonstrate they use all of it, they will get the same again, or even more!infact if you don't spend all your budget you are liable to have less allocated for the next financial year.
I don't think anyone actually checks what exactly they use it for, as long as it falls within means of the department. e.g. A way to use up a budget for the local council, is to just dig up a street - then decide what to do with it later on....if they decide to do anything with it at all! It's a good idea, from their point of view, because they can always use whatever they decide to do with it as an excuse for more budget!