I'd go further and say that all "drugs" should be easily available and the tiny percentage of folks who develop dependency issues should be provided treatment and support.
Not only would this reduce suffering and provide a wider range of pain management strategies, it would also significantly reduce the societal costs of substance prohibitions in terms of reduced economic impact in the following (not a complete list) ways:
1. Interdiction/enforcement is hugely expensive, and providing treatment to those who require it would cost a fraction of that;
2. Criminalization of substance use stigmatizes those who are caught in that particular net and, at least in the US, limits their ability (because many folks won't hire you if you have a criminal conviction) to increase economic activity/output;
3. Because of (2), many communities as well as the economy as a whole are negatively impacted both economically and socially;
For some reason, when it comes to "substance" use issues, we tend to examine the possible alternatives to address them, then choose the least effective, most harmful one.
I hope that changes, but I doubt I'll live to see it.
Edit: Clarified that the impacts I mention are not all of the impacts that drug prohibition has on society.
They used cannabis to manage their pain for two days and never filled the script. I think a script for two or even three days would have been perfectly reasonable with a "Call me back if the pain is too much after that period".