I definitely disagree with the comments that being picky is something that people should grow out of with food once they become an adult, the reality is some people just don't like certain things - I'm a bit of a texture freak so certain things immediately turn me off (although I also eat some tings that have MEGA weird textures that others hate), I'm also a weirdo when it comes to dips/spreads/salad dressing and won't use most of them (to the point ranch or caesar dressing make me nauseous if I smell them). I still eat things like salads, I eat most every ethnic cuisine and I am definitely not afraid to use spices in my cooking, but definitely would still call myself picky (mainly because I have to ask for modifications to a lot of food at restaurants).
I think the distinction with someone like Zoe is the KIND of picky she is. It's very infantile. She eats either what a child will eat or maybe the odd thing on instagram (like things with a balsamic drizzle). It's always got to be something sweet - even the healthier things like yogurt are topped with lots of fruit and honey and the health becomes fairly overwhelmed by the toppings. It just seems that any real, whole foods she uses are strictly for aesthetics and not something she eats because she enjoys or will be good for her - the tomatoes she has at breakfast are always on a vine, fruit is used to top things and add colour. She never had to grow up. Most people move out of their parents house, often eat like shit for a year or 2 because you can, then they grow up. She was encouraged to keep going - with her weight and her target audience. She never had a reason to do otherwise it seems, apart from the health effects but you know she blames that on literally everything else.