You used to - like a century ago - be able to buy things like cocaine and methamphetamine OTC at pharmacies and they were not as big of a problem as they are today. A lot of today's problems come from things outside the drug itself. Most overdose deaths, for example, come from the drug user being wrong about the amount they're injecting because their dealer lied to them, or didn't know themselves because their dealer's dealer's dealer changed supplier, and didn't notify those downstream because reliable communication is difficult because of the police.