See The United States thinks that just because they are able to isolate and determine the active chemicals in hallucinogenic plants that they are not appropriate for use. It is that they do not respect other ways of healing. See in United States healing is not Spiritual because it is considered superstition, Healing is scientific. And if Healing is considered non-spiritual then they obviously don't believe in god and don't respect those that do and believe that there is a spiritual aspect to illness and that in some people beliefs whether "official" or not rituals involve the use of drugs.