Why is herbal medicine so unpopular?

A lot of people use herbal medication. The only requirement is knowing where to look. I can assure you that a medical pharmacology database won't be your best resource for details on alternative medicine, nor will it have the right references or even let you know where to look for the right references. Your search is in the wrong locations; it has nothing to do with its popularity or lack thereof. Because of the way our regulatory system is now set up, most "drugs" are synthetic. Don't undervalue the substantial impact that pharmaceutical firms and health insurance providers have had on both traditional medical education and the regulatory framework for drug approval.