Following the recent tipping question, what's a good wage for a server? What are they paid outside the US?

Since ours in the US is generally a percentage of the bill, people in expensive restaurants can make more. Do they work harder? Do they have fewer tables so less checks are tipping? 20% tips on 5 hundred dollar tables is $100 every 60-90 minutes, but shifts are usually only a few hours. So maybe $3-400 for a 4-5 hour dinner shift? In a diner you'd are probably half that per table but for more tables and faster turnover. What's a good wage?