The technology already exists: as other people have pointed out you can get test kits for fentanyl pretty cheap. And that applies to almost every drug too, you can buy Marquis reagent which covers most commonly used recreational drugs. But people really are not used to the idea of testing their drugs: when was the last time you bought a shot at a bar and tested it to see if it contains methanol, or checked if aspirin from your pharmacy is actually aspirin?
We don't really need to change an entire society, all we need to do is legalise and regulate recreational drugs. That immediately solved the problem of missold drugs. The societal stigma which prevents people seeking help for addiction might not vanish overnight but it's impossible to do anything about it while drugs like opioids are illegal.
