This is why it doesn't happen: politicians get bought.
"Jeffries co-sponsored Medicare for All legislation between 2013 and 2021, but in August 2026, he stated he shifted his stance and stated that he no longer supports or co-sponsors the proposal." https://en.wikipedia.org/wiki/Hakeem_Jeffries#Healthcare
This could equally be explained by wanting to be perceived as more moderate/centrist. Which would make sense for someone in a leadership position.
There are many reasons Jeffries might change positions; why do you say the reason was that he was bought? Is there evidence?
Many Democratic politicians are moving away from progressive positions, including Ocasio-Cortez. They seem to be following the old (and failed) Democratic Party tactic of moving to the center to get elected.
One of two major political parties, and the one that currently holds all 3 branches of federal government, has labelled it un-American and communist. And yet you point the finger at...a Democrat.
Universal healthcare doesn’t happen in the US because a certain subset of the American population would rather have worse health outcomes than guarantee abortions, HIV prevention, and gender-affirming care.
Also, ~150M people with employer coverage plus seniors on Medicare fear disruption more than they value expansion.