Yep, me too. A drink is just that, what it is made up of is immaterial. The JSP is the written deliberately so that local commanders do not place an extra limitation upon existing limitation.
One problem with capped is when you find yourself in US BoQ for a period of time. Going out to eat and provide receipts is all very well but if it means having to get up an hour earlier to find a breakfast bar and then having to plough through a US breakfast but after a week of that regime, your liver and other parts of your digestive tract will not get the joke. There is not the ability to produce supermarket receipts for some cereal and pint of milk a day.
Finally (apologies if someone has raised it earlier), I defy anyone to feed themselves to a reasonable standard for £21 in London. Cup of tea alone is £1 to £1.50. A lunch in a TA Barracks is £12. There is over half my entitlement gone without my having breakfast and I still have evening meal ahead of me. We have been seen off.