Do you have more info to support the "usually of very questionable quality" claim?
Edit: corrected "low" to "questionable".
Edit: corrected "low" to "questionable".
Usually it's highly bureaucratic - you have to "climb a ladder" of doctors. First your GP, then a specialist, then, maybe a hospital. You wait a lot (sometimes weeks and months, because you are not "emergency"). And sometimes you encounter outright incompetence and have to go to a private doctor/hospital to have your problems properly attended to.
That summarizes my experiences with the healthcare systems of 4 different EU countries.
The use of "questionable" in that way is a bit idiomatic, I think, as a polite way to say something is bad.
Not to say that there aren't also significant problems with US healthcare.