Kids in my daughter's middle school were vaping. According to my daughter, a kid's mom was selling vapes through them to kids in the school. There will always be a market to sell kids contraband and plenty of kids will be happy to pay a premium for it regardless of what their parents say.
But in this case, with gender affirming care, it's generally a case where the parents also want the child to have that care. It's being denied despite what the parents, the child, and even their doctor wants.