Why is Fentanyl a schedule II substance (in the USA) While heroine is a Schedule I substance?

I don't agree with drug prohibition but correct me if I'm wrong, Isn't Fentanyl more potent than Heroin? Even if it isn't, aren't they both extremely potent opiates with a strong potential for abuse? Why is heroin a schedule I substance (which means it supposedly has no medicinal value) while fentanyl is a schedule II substance (which means it is supposedly a potent substance with a strong abuse potential but a doctor can legally prescribe it and use it on patients)? It's interesting to note that (crude) cannabis as well as LSD and psilocybin are schedule I substances even though they have noted medicinal potential and are less harmful than many schedule II substances (like cocaine and methamphetamine).