That because the vast majority of people don't know the details of single payer/medicare for all. Both single payer/medicare for all will call for a tax increase across the board. Granted the tax increase will replace the premium hikes, but I just don't know how you can sell that to suburban Americans.
I don't understand this type of thinking. Yes, taxes will be raised, but people will no longer have to pay for the vast majority of healthcare, and they are guaranteed care to the end of their lives. This is no different than Social Security or Medicare, and those are some of the most popular government programs in the United States.
It is not hard to understand, Americans hate taxes, even when they are getting a good deal out of the increase.
This is why a public option is a better sell, if done right it would be self sustaining and require no tax increases just people paying premiums/deductibles.