Check out wages in Sweden, Switzerland, Finland, Norway, Denmark. I can't point to a summary table but you can read what people write or say who live there. I have many friends and traveled to each country many times in the past and from what I heard many restaurants pay their waiters a very good salary (far above Usd 20 equivalent). Does not matter whether the waiters receive tips or not. What matters for this particular discussion is that the employer pays out that much.
As a matter of fact, the minimum hourly wages in most western and industrialized nations are almost all at least 50% higher than the one in the US. Their small businesses seem to survive at similar rates than in the US. In the OECD only Turkey, Israel and Russia have lower hourly minimum wages than the US.