In the UK.
However I am mostly referring to Scandinavia. You have many really small places where everybody knows everyone, so the local doctor will treat their friends, family, even people they've fallen out with. And their dating pool will be the same community.
It's not that different even in cities with 300,000ish people.
People have somewhat of a preference to get things done within their circle, e.g. go see a doctor, lawyer etc that they know.
Obviously my personal experience is more historic, so say the 2000s, but I actually know my cousin who's a psychiatrist and she has her sister as a patient. In fact, another cousin is also seeing a therapist, and it's also a relative. My aunt treats probably every single family member that needs her specialism.
That part to be honest I don't get, I don't think I'd want someone I know as a therapist.
But there's a very strong trust in patient confidentiality, and suppose people feel they can trust someone they know more with their confidential health issues than a stranger. I think another part is access to the system, you can access specialists without GP referral but the waiting lists are long, so people like to text a doctor they know to see if there's any last minute slots available etc.
Medical malpractice is a thing but from what I hear, serious complaints aren't that common, although I have heard of a couple of cases. Though I also believe it's changing gradually. From what I hear, in the UK medical professional live in constant fear of being reported and take safeguarding very seriously.