I've seen them used in large outdoor town festivals in France, where there are lots of kiosk type bars scattered about the town. It means that there is not actual money in the tills - so, in a situation where you have lots of temporary staff working, who might not be well known to the concession owner, there's not such a worry about tills being wrong or wondering if anyone is making mistakes or, worse still, nicking anything out of the till. If someone were to rob the kiosk, they'd only get beer tokens which would have no cash value beyond the dates of the festival either. No-one's trying to cash up in a busy area - much simpler all round really

Suppose it's just a loophole closing which makes things more secure from a cash handling perspective.