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)