> Which you won’t be able to do if the cost of prosecuting someone increases several times (i.e. no plea bargains anymore).

Well sure you can. It just costs more. But since you're still doing it, the deterrent is still present and then the expensive cases you have to prosecute remain rare.

> Aren’t these already (realistically) misdemeanors at most in a lot of places?

Not for the sellers they're not.

> Are you suggesting legalization?

Yes.

If you could go buy codeine or lisdexamfetamine for $5/bottle from the pharmacy counter at Walmart then there are no more drug cartels, no more drug cartel murders, no more street pushers lacing what was supposed to be MDMA with fentanyl that causes people to OD or get addicted to opioids, fewer addicts robbing people for drug money, higher deterrence for other crimes because police aren't spread so thin, less poverty and desperation because fewer kids have fathers in prisons or coffins, fewer neighborhoods held hostage by drug gangs.

That's a whole lot of crime that just goes away.

More to the point, consider where we are in terms of efficiency. It costs on the order of $100k/year to incarcerate someone. Every one of those drug murders you prevent is saving twenty million dollars worth of keeping someone locked up for two decades. That pays for a lot of two day jury trials for petty theft.