An adult can choose to eat it or not (I'm ignoring the addictive nature of concentrated sugar), but our public health establishment has been foolishly stupid (combined with industry marketing) at making people think that fruit juice is natural or healthy. It's about as natural as cocaine is. Sure, it comes from a plant, but it gets refined and concentrated into levels that are unheard of in nature and toxic to the body.

Virtually my entire extended family are working class people, and they all were feeding their kids apple/orange juice on a regular basis without diluting it. When I showed my sister that she could literally do a 5% solution of apple juice in water, and it still tasted sweet, she was blown away. I'm pretty sure most members of the laptop class know that juice is bad for kids (gatorade too), but that message hasn't filtered to most of the population. And these kids are too young to know how toxic it is for them.