Simply put, it's a trust issue.
I think in many places people establish a relationship with their primary doctor, where the Dr knows them and their medical history in detail. Growing up, my family doctor had treated my family for generations and was familiar with me as a person even though I did not have many appointments.
But since I've moved to America most of my Dr. appointments are focused on the issue I am having as opposed to treating me for an issue. The Dr skims through my medical history to see if the issue relates to anything relevant. The appointments are hurried and impersonal.
There is a business aspect to medicine in America- it's business more than it is healthcare, really. I have often felt more like I am going in for maintenance like a machine than going in to speak to someone who uses their knowledge to help me be the healthiest I can be.
I know a lot of people here who also go to doctors and have their issues dismissed, minimized, or attributed to stress- and leave without any sense of what to do, besides grab a prescription or see a specialist. There is a helplessness I perceive in many people, and some end up with many prescriptions for different things and later find out there is an underlying issue that was overlooked all along. There are many many stories of people whose problems may not have persisted so long if their medical providers had communicated better- which perhaps most of them have no incentive to do, because this is time consuming and therefore loses them time/money. Whereas in a system where private doctors have to conpete with state provided healthcare, my anecdotal belief, they have an incentive to do better.
Anyway, having an impersonal system leaves people feeling like they need to look for solutions themselves, looking for hope at a cheaper price than a stack of copays and possibly having to deal with waiting long times for referrals. This is also true of anyone anywhere feeling desperate and looking for some control in regards to their health problems. So this opens the door to a market of people offering miracle cures. Just happens to be there is a lot of distrust baked into the reality that healthcare in America prioritizes profit over people.