From the perspective of most of the world, having to limit yourselves to medical care that's provided by a particular company seems very broken. (unless I'm misunderstanding how Kaiser works).
I can just go to whatever walk-in clinic, urgent care provider or emergency room I need, depending on the severity and get treatment (I do try to go to my GP if possible, but I have many options if that's not practical for some reason).
Most countries that have socialized healthcare still have private providers - the government is paying for healthcare, but they're taking on the role of the insurance provider rather than the healthcare provider.
I can just go to whatever walk-in clinic, urgent care provider or emergency room I need, depending on the severity and get treatment (I do try to go to my GP if possible, but I have many options if that's not practical for some reason).