Here's a good overview of how they go about making sure that approved drugs are GRASE (Generally Recognized As Safe and Effective): https://www.fda.gov/Drugs/ResourcesForYou/Consumers/ucm14353...
Publication bias is a real thing, and drug companies do know how to use it to their advantage. Take a look at what drug trial results looked like before and after the FDA started requiring pre-registration. The difference is, to put it mildly, staggering.
I'm pretty hard pressed to come up with a market equivalent to drug trial pre-registration. Given everything I've seen of Adam Smith's writings, I'm pretty sure that, were he alive today, he'd probably say something like, "Duh, of course. Do that. That is some excellent regulation, and obviously in the service of the public good."
Tangentially, I'm guessing that, if CBD had to go through pre-registered drug trials, it wouldn't be such a big deal. The funny thing about things that are widely believed to help with every last ailment is, they tend to all be about equally good at treating pretty much everything.