Senator Bernie Sanders, Elizabeth Warren, Cory Booker, and Jeff Merkley, are introducing a Medicare For All bill in the Senate. It’s a model for where this nation needs to be headed.

Some background: American spending on health care per person is more than twice the average in the world’s 35 advanced economies. Yet Americans are sicker, our lives are shorter, and we have more chronic illnesses than in any other advanced nation.

That’s because medical care is so expensive for the typical American that many put off seeing a doctor until their health has seriously deteriorated.

Why is health care so much cheaper in other nations? Partly because their governments negotiate lower rates with health care providers. In France, the average cost of a magnetic resonance imaging exam is $363. In the United States, it’s $1,121. There, an appendectomy costs $4,463. Here, it’s $13,851.

The French can get lower rates because they cover everyone — which gives them lots of bargaining power.

Other nations also don’t have to pay the costs of private insurers shelling out billions of dollars a year for advertising and marketing — much of it intended to attract healthier and younger people and avoid the sicker and older.

Nor do other nations have to pay boatloads of money to the shareholders and executives of big for-profit insurance companies.

Finally, they don’t have to bear the high administrative costs of private insurers — requiring endless paperwork to keep track of every procedure by every provider.

According to the Kaiser Family Foundation, Medicare’s administrative costs are about 2 percent of its operating expenses. That’s less than one-sixth the administrative costs of America’s private insurers.

To make matters worse for Americans, the nation’s private health insurers are merging like mad to suck in even more money from consumers and taxpayers by reducing competition.