Is the threat of criminal punishment the only incentive that works on you? You never do things because it would make someone happy or you a better person?
This isn’t about me; let’s not make this personal.
The question was, “why shouldn’t doctors be required to treat patients?” It wasn’t,
“should doctors treat some patients regardless of ability to pay?” There’s a big difference between these. The first is about compelled behavior; the second is about voluntary behavior.
There’s an analogy in the legal world in the U.S.: while lawyers aren’t required to take cases for free, there’s a time-honored tradition of reserving some time to take some cases for free (aka pro bono).