@kaia marketing is a language on it's own. If it says "100% fruit juice concentrate", it's probably ~50% apple juice because cheaper. If it's "100% orange juice", they can still add more water than what was originally in the fresh juice, making it thinner. That's why 100% direct juice" is a thing. "100% nectar", on the other hand, is just fruit juice based sugar water.
Some declarations are really tightly controlled, but only if they actually apply to the product name. And there are plenty of creative naming shemes to avoid that. :comfyevilplot: