Everyone in the US seems to act like it's normal. (Every hospital records an individuals "Primary Care Physician", for example, as if that was a real thing that actually exists for people).

But in practice, I've never seen anyone whose life was (A) wealthy enough and (B) consistent enough, to regularly see the same doctor for more than a few years at a time. People move, people change jobs (which changes insurance, which changes allowed medical networks), and so on.

I don't doubt it happens, it just certainly doesn't feel like the common case, even in the US.