Earlier quoted context omitted.
The problem with single payer is that it results in shortages. Look at waiting lists for the NHS, especially for mental health or routine surgery. That is a direct consequence of single payer. An unpopular view, but it is a fact.
I am skeptical of a causal relationship there. In the United States, approximately 2/3 of healthcare costs are already borne by the government. My parents are both enrolled in Medicare and they are very satisfied. Why would it not work if we just dropped the eligible age for Medicare to zero? Hasn't this been extensively studied recently?
Less than half; US healthcare spending was around 8.5% GDP public, 8.8% GDP private in 2016.
https://www.healthsystemtracker.org/chart-collection/health-...