I like the system in Singapore. Organ donation is mandatory, though you can complete a form to opt out. If you're on the opt-out register, you have a lower priority to receive organ transplants. Fair is fair.
I feel like Singapore should be the gold standard of how to do most things that don't involve the justice system or surveillance. They seem to do most things right. Or maybe I'm just getting a golden picture? Lol
This is often seen as a positive measure as well, because it reduces the risk of bribery and other sorts of corruption. One wouldn't risk an already great income for a chance to get a little extra.
I think there are examples of it working, and examples of it not. Singapore's system works as intended, but here's a list of yearly salaries for high-paid heads of state >$500,000 USD (sources from Wikipedia). Draw your own conclusions.
Cameroon President: $620,000
Denmark Queen: $11,000,000
Hong Kong Chief Executive: $568,000
Japan Emperor: $3,000,000
Jordan King: $848,000
Kuwait Emir: $165,000,000
Luxembourg Grand Duke: $12,000,000
Norway King: $33,000,000
Oman Sultan: $7,000,000 (could be a very old number)
Qatar Emir: $33,000,000
Saudi Arabia King: $9,600,000,000 ($9.6 billion)
Singapore President: $1,400,000
Singapore Prime Minister: $1,600,000
Switzerland President: $507,000
Syria President: $576,000
Tonga King $2,100,000
United Arab Emirates President: $4,600,000,000 ($4.6 billion)