The market is very good at sorting these things out. Plenty of people buy snake oil. Look at the vitamin/supplement market. Most of that is unproven but people take it anyway. If you have a new drug the reason you will still do trials is because of marketing. Companies send their stuff to UL for testing so they can get the UL Label. You can still have the FDA running trails but instead of banning sales of drugs they just give their seal of approval.
If you are risk adverse you may just stay will older more well proven drugs. If you accept risk or are desperate enough you may try more unproven ones.