My issue with a single-payer system in the US is that it won't get rid of the middleman. You are essentially replacing a bunch of insurance companies with one insurance company, which is the government.
Hospitals can now charge whatever they want and the cost continues to skyrocket. This is exactly what has happened with college loans.
I would rather the hospitals have to charge patients directly, which would drastically reduce costs..and then have a smaller layer of protection for people that can't afford it.
This is not how things work out in practice. Larger payer pools end up paying less, because they have enough market power to force providers to meet cost targets if they want access to the customers in the pool. Medicare famously gets much more out of each dollar it spends than does just about any private insurance provider (see https://www.healthaffairs.org/do/10.1377/hblog20110920.01339...).
A single-payer system just takes this to its logical conclusion and creates a single pool with nearly everybody in it. That pool is so large that only niche providers of extremely high-margin services can survive without access to it, so the single payer has the leverage to drive the rates it pays down to the bone.
Hospitals can now charge whatever they want and the cost continues to skyrocket. This is exactly what has happened with college loans.
I would rather the hospitals have to charge patients directly, which would drastically reduce costs..and then have a smaller layer of protection for people that can't afford it.