Whilst I don't think the server in this case was working the volume someone at a cheap bar would, I typically see a server in a nicer higher end restaurant serving 6 or so tables during dinner. If every table was tipping ~ $100, that is ~$600 over the course of 2-3 hours, or $200 per hour. Even allowing for taxes, tipping out, etc. that is a hell of an hourly wage.

This whole 'it's how people make a living' just doesn't really fly when we are talking about high end restaurant servers (different ball game at a roadside diner etc). They make FAR FAR FAR in excess of minimum wage (which, incidently, they would receive if customers tipped absolutely zero on each and every check) and by many high-end restaurant servers' own admissions, make six-figures annually.