CrossFit costs more because a certified coach plans and supervises every class in small groups, rather than selling unsupervised access to equipment. You are paying for expert coaching, structured programming, form correction, and community, which is closer to group personal training than a traditional gym membership.
This is a direct answer from the CrossFit BC coaching team. Short version first, then the detail and the local context for training in Vancouver. If you want the same answer applied to your own situation, a coach will walk through it with you in person.