Yes opioids are powerful and potentially dangerous drugs, but used wisely they are very useful and effective. If there is a problem then the solution is to solve the problem, not just ban everything because there might be a problem.
On the topic of the US opioid addiction the way it has been handled is appalling. Getting millions hooked on powerful prescription opioids and then cutting them off cold turkey with effectively zero help so they end turning to really dangerous drugs like fentanyl is criminal.
Nothing works as well for a nagging cough as codeine and terpin hydrate. Nothing.
Unfortunately, you've got to go to a doctor to get it nowadays.
Instead, most people use OTC stuff with DXM (which doesn't work as well, is an abusable drug in its own right, and is quite likely more toxic than the codeine).
As for why to not make it prescription only is we have universal healthcare in Australia. Shifting low dose codeine to prescription only will cause a massive increase in doctor visits at a huge increase in the cost to the Australian tax payer. I use OTC codeine to treat and catch my migraines before they become major. I maybe take codeine once a month and never visit the doctor. I will now have to visit at least once or twice a year for no reason other than to get a script for something I have been buying over the counter for the last 30 years.