This is a perfect example of too much government.
I love to tip, almost always get great service.  I know I am tipping someone who makes big bank at the end of their shift.  Min wage or no min wage.
Portland is a great town and many servers earn a great living.  Government mandates on wages changes all this.
Restaurant owners MUST make a living also, and I would be shocked if some servers don't make more $$ than their owners.