I work part time at a local fueling station so I see this from the other side as well and the following is a few things you people calling her a jobsworth should understand.
1) The Garage I work at has some utterly insane rules when it comes to authorising pumps, most of which get ignored on a near constant basis.
2) Whoever is authorising the pumps is considered responisble by the company for checking that every pump they authorise is legal and safe, remembering the order in which customers fuel and ensuring that all customers pay for their fuel.
There are ten pump fueling points where I work, on a busy day they are all constantly in use and this one person is expected to keep track of all transactions, the order they happen in and serve customers in the shop at the same time, remembering to offer each and every one of them a coffee, ask if they have a nectar card and offer them one if they don't, all the while keeping the queue to a maximum of two people... if say pump 5 has three queued fuel transactions of say £10, £25 and £50 and the assitant on till three mistakenly lets the guy with £50 pay £10 by mistake it is still considered the fault of the person authorising the pumps.
There are four tills, only two of which can authorise a fuel pump. Till 1 is the position of authority and whoever is on till 1 bears these responsibilities regardless of the assistant on till two just authorising pumps without looking, obviously this is site specific, but I'd imagine a lot of stations are the same.
3) When a drive off happens (and they do, quote often) the person who was authorising is held responsible and will depending on previous records end up with a disciplinary, which could easily lead to being fired, this has happened.
So in all, the assistant can, through absolutely no fault of their own come into a situation where their job is threatened and they will have to attend disciplinaries and extra training.
It is not suprising therefore that sometimes you will find one who has been ****** off by the management and will be working to company rule, it wont be aimed at you, it will be aimed at showing the management that their rules are over the top and if they are enforced as the company insists people a) complain and b) go elsewhere.
Next time it happens, ask to speak to the manager and give it to them as it's likely not the assistant being a jobsworth, it's the company forcing it on them via their utterly stupid operating proceedures.