A lot has to do with the availability of health care in Europe (universal health care), and specifically addiction care.
I'd wager that Europe and most of the world was slower--thankfully--in adopting a new painkiller like Oxycontin and dodged a bullet, by seeing what the US was already facing.
https://www.latimes.com/projects/la-me-oxycontin-part3/
A lot has to do with the availability of health care in Europe (universal health care), and specifically addiction care.