If grandma decides to purchase opioids illegally rather then get treatment that's 10 years in prison in Singapore. The law is effective in this case of making grandma pursue the correct treatment.

This is not all. Executions will occur: namely the parties responsible for the opioid epidemic will be put to death without regard to corporate shielding. Courts will determine on an individual basis who was responsible and hang them.

I believe this last point is something I wish would happen and would largely be an effective deterrent. It is entirely a matter of how much power a DA will have in pursuing such "policing" policies. The former point however is true and is the outlined procedure enforced by the government in Singapore.

Either way even without the last point I think I have shown you that "policing" can be effective. It really depends on how much policing and how severe it is.

There is the obvious side effect of possibly creating a police state by giving the police/government too much power. But while the phrase "police state" has bad connotations it is arguably not always a bad thing as exemplified by Singapore.

I don't know whether such policies will be effective in the states. But it is patently false to say that policing cannot be effective.

It is easy for a person to hold loyalty to an idealized concept that "policing" doesn't work when it comes to drugs. The reality is, like almost everything in life, much more nuanced. Ask questions. What kind of policing? How severe? Being open minded means that you need to ask those questions rather then deliberately constructing logical scaffolding to support your preconceived/popular conclusion about the US drug war.