You get a check for X. The cardiologist gets a check for X, and also gets the income from working as a cardiologist. He/she then pays taxes on that income, which leaves him/her on net probably at least somewhat worse off than today, but still better off than you, who only get a check for X. It's that "better off" part that motivates the cardiologist.

Do you think he would vote for that? Or, like similar systems in the last century, would some, let's say state encouragement, be required?

No he wouldn't vote for that, but what does that have to do with your original question?

And I feel like you're being very disingenuous by implying that him not getting what he voted for is equivalent to communism.

It isn't the original question, but I thought it was a legitimate one.

The cardiologists and their like can be outvoted. That's how it goes in a democracy. But the number of people who lose on net may be greater than the number of people who win on net. So the only way it gets implemented may be through... let's say "undemocratic" means.

Note well: I'm not advocating this. I'm just pointing out that this may be the way the politics works out.

Sure, I can imagine the points grb423 may have been implying, but by presenting them as a series of vague rhetorical questions it makes it hard to respond directly.

Because there is a good chance that X is going to be less than what either you or the cardiologist already make, but it may be more than what a janitor does make. So the cardiologist and you keep working, and the janitor has an incentive to quit performing a mindless job... and maybe become a cardiologist.