I agree with you on many prescriptions, but many have a legitimate need to be regulated.

Antibiotics are an obvious one. Antibiotic resistance is a real, and growing, issue. If people start popping them every time they get a sniffle, that's going to get a lot worse.

Some medications have very serious side effects, and a doctor really should vet that you're healthy enough to withstand those.

Some medications can have very severe interactions. Part of the prescription process is that their computer is supposed to alert the pharmacist if some combination of the meds you're on creates an issue.

Honestly, those few categories knock out most of the useful medications. Mental health drugs are generally safe, but self-medication isn't usually effective in those scenarios.

Ok. Let's not unschedule antibiotics. But there still are many prescription medications which are either harmless (at least not more dangerous than Tylenol is) or so specialized most of the ordinary people (who doesn't actually need them and doesn't know the relevant details) don't even know they exist. In fact Tylenol is extremely dangerous (quite easy to kill yourself with it) yet widely available and nobody seems to consider this a problem.

This wouldn't happen. Even from a pharmaceutical company's viewpoint, their regulatory body comes down on them like a ton of bricks if too many people suffer injury from their products.

So pharmaceutical companies and other medical product manufacturers manage their risk by only selling to approved suppliers, so that they don't have people randomly putting themselves at risk using their products.

It should be enough to put a clear warning on the box saying you take all the risk yourself if choose to self-prescribe and also list all the known interactions and counter-indications somewhere in the manual. This works just fine in some countries. You can't drink a chemical potentially poisonous to you after being warned and still sue the vendor like if they didn't tell you shouldn't.

As someone who works in medical devices I can tell you in the medical field it's not enough to just write on a box "If you use this incorrectly and get injured, it's not our fault"

Medical products have risk assessments a mile long for every scenario the manufacture can think of, and the mitigation for being administered on the wrong patient is often "Don't sell to non ISO-13485 approved clients"

If enough people get injured because of your product, the FDA or MHRA is going to investigate you, no matter how many disclaimers you put on your products.