Yes, they do, and I gave you evidence that they do.
Depends. If you are unconscious, then you can't shop around. If your injury is such that you need immediate medical attention, then you can't shop around.
But for everything else, you can shop around, and emergency care is only 2% of all healthcare spending.
But many don't, hence you're wrong.
That's all it takes. If you say there are no white squirrels, all I need to do is find one white squirrel to falsify the claim.
And it's not just a "handful of anecdotal examples":
Aren't you getting tired of being wrong?
If single-payer was superior to the market regarding healthcare, then single payer should also be superior in many other markets. Do you support single payer for housing, food, or transportation?