> My point is although there is no question you are subject to the actions you (and others describe) but it also could be the case that it happens for other reasons that have nothing to do with skin color.

I think that is a bit of a stretch. There is concrete evidence that explains this happens a lot, and it's clear that racism [1] and sexism [2] are a key part of it.

And -- not as scientific here -- but there's intuition I have gathered that's backed up with 10 years of extensive dining out in various arrangements and settings, and anecdotes from my server friends about the politics in restaurants.

[1] http://tippingresearch.com/uploads/Business_Considerations_T...

[2] http://tippingresearch.com/uploads/ServerAppearance1-3-08.pd...