At one time in the not so distant past in the United States one could go down to the local drug store and by cocaine. Think Coca-cola. The current drug laws are all recent. The US operated for about 150 years with no problems with the drug laws. Think about it.
All these things were sold in stores. Cocaine, cannabis, heroin.
Then pharmaceutical companies got skilled at making artificial drugs. They realized that they could make a lot more money by creating artificial drugs and then patenting them and selling them than they could by refining natural substances. After that, most of the natural drugs were made illegal. The artificial replacements are available by prescription.