Due to end user advertising the US a lot of people are tuned into taking drugs. It's just a part of life. I am 50 and people seem to be baffled when I tell them I don't any prescription drugs unless I have something acute. I see tons of people taking antibiotics and pain killers immediately when they have a problem. That starts from childhood on.
Doctors in the US are really quick prescribing hardcore drugs. I have had several occasions when I had an injury like a bruised and got a Cocktail of vicodine and muscle relaxers. They make you feel real good quickly and I can totally see how people can get addicted. In addition people who have withdrawal symptoms get cut off cold turkey and get no help. I guess that's even more so in low income populations that barely get any healthcare.
Why is this not a problem in other countries? Either the number of people suffering from chronic pain in the U.S is way higher (percentage wise) than in other countries (why?) or the doctors are prescribing extremely dangerous medicine as if it were candy.