First of all, what Bernie wants to do will cost an atomic shit-ton of money. Money that just isn't there, unless you want to get taxed up the ass. The math just doesn't work, and he knows that. Pretty much everyone should know that.
Also, when it comes to the quality of medical care, the price is only one aspect of it. Socialized medicine is great as long as there is nothing seriously wrong with you. When you are seriously ill, wait times become very important. Life and death important.