Well then the tip depends on quality of (eventual) service no? And I'd even say one of the determinants of service quality would be how long you had to wait in line.
Maybe, although in my experience in America you almost always need to wait in line, even for a steakhouse. In Europe, much less, in London a few restaurants but I don't recall ever needing to wait in other countries.
So as a foreigner what I don't get tis shouldn't not getting paid the fair wages drive down demand for these kinds of jobs? Am I in the minority in beleiving that customers will pay what they are charged upfront instead of extra sneaky costs. (Btw I will definitely tip for exceptional service but I think bringing me food and not throwing it on the table is kinda bare minimum:) )