Both my kids are Gen Z and at least from my experiences talking to them and their friends, one of the big factors is no one taught them when they were young. I'm not talking anything formal, just helping out in the kitchen, chopping veg, grating cheese, whatever. Either their parents don't cook or they didn't let them be active participants in meal prep.

My kids however do know how to cook, as they've helped out since they were little. Learned from my own experience as a picky eater - get your kids involved in making stuff and you won't have to worry about them only eating chicken nuggets or whatever. Once they were teenagers, they got assigned meal prep once a week - they'd pick a recipe, help with the shopping, and make dinner (with help if they asked for it). And now they're both adults who can make their own food. It's shocking to me though how many in their generation just were never given the chance to learn the basics when they were young.