I have been told that it's also due to the fact that in Europe, people generally travel through a unified medical and social system from birth; if they exhibit

I have been told that it's also due to the fact that in Europe, people generally travel through a unified medical and social system from birth; if they exhibit problems they are directed to the necessary interventions (mental health services, addiction, etc.) Providing these services earlier on with a full picture has a higher ROI than intervening later without all information about that person's journey. Additionally, I believe that for people who are seriously mentally ill, it's more difficult to section them in the US. In the UK, it takes a GP and social worker to section someone; I believe in the US it's not that simple.