My slight adjustment to your plan (but probably still controversial):

Anyone can receive a donated organ. But those that do are permanently opted in to donate.

Well, I actually don't think that. People can legitimately change their views and philosophies. The "wedginess" of this rule would probably do more harm to society than the marginal increase in organ availability.

"We could very easily save your life with a transplant, but we won't because you did not choose to be an organ donor" is not something I think people in this country have the stomach for. This would be like if we didn't treat people who opt not to carry health insurance. In theory that prevents moral hazard, but in practice no society would be willing to let people with treatable ailments die.

The NHS has budget constraints so they are making this kind of decision all the time. It’s unlikely to be made by the doctor treating the patient anyway.

You don't say why you want to do this.

I think it's perfectly fine and respectable for someone who opts out of donation to decide for themselves, when the issue faces them, that they won't take a life saving organ.

That's very different from mandating and coercing organ donation in order to be eligible.

Right now, organ donations go to those with the greatest need. You are saying, well no it shouldn't go to people who aren't moral according to my philosophy.

I think you have to consider how that could go wrong, and who might be considered the wrong sorts of people, the sort of people who don't deserve to be treated.

Who might prominent political figures decide are immoral, abnormal, unproductive, unworthy, or unpatriotic?

IIRC this is how it works in Singapore.

Yes, let’s shame and punish people that think differently than "the good way", it will totally help the cause get more support.

There are long waiting lists for organ donors; why should I donate my organs to someone who won't return the favour? I'd rather donate them to someone who would.

But that's only fair.

As an analogy, it's like healthcare/insurance taxes - you pay them regularly in the hope that if you ever need it, they'll pay for you.

Why would you expect to receive an organ if you're not willing to offer yours?

It's not just that; it's punishing people who want to benefit from a system they refuse to "pay" into.

What if I off-shore my earnings to avoid paying tax; what if I vote Republican. Does consenting to organ donation make me a worthy person despite anything else you may disagree with?

Reciprocity is not some outlandish concept: If you're unwilling to help out, you don't get to join the mutual aid pact.

That’s irrelevant. If you just treat organ donation as an exchange system, an “organ-bank club” if you will, you don’t need to bring judgement into it.

Parent post was hinting at judgement though.

No shame, no punishment. It’s just an organ sharing club, join it or don’t join it.