Whole Earth Organic Cranberry drink

You're in a health food shop and you see a can of Whole Earth "Organic Cranberry".

Naturally you assume it's full of cranberry.

But when you get it home, and look at the ingredients, they look like this:

Grape juice (54%), cranberry juice (4%), aronia juice (0.8%)

If I'd wanted grape juice, I would have bought grape juice.

Other drinks in that range are similar:
Elderflower: 59% apple juice, 3% grape juice, 1% lemon juice, with just "elderflower flavourings"
Orange and Lemon: 60% apple juice, 10% orange, 1% lemon.

How are companies able to get away with this? Sure, if it was called a cranberry flavoured drink, maybe, but there's nothing to suggest that it's not majority cranberry.