[timwiseman]

1) Anyone who bought a house is just as guilty of precipitating the crisis as the banks...

This is true to a degree. But remember that banks and real estate investors are expected to be much more knowledgeable and sophisticated players in the market than someone buying one house as a primary residence.

Similarly, the societal norms when hiring a web designer are different from the norms when dealing with a waiter. You tip your waiter, you don't tip your web designer.

I am a DBA, not a web designer, but I have gotten bonuses above and beyond the agreed upon minimum in both full time and contract work. This is very similar to a tip and often they arrive at the number in a similar way (a percentage with percentage based loosely on their evaluation of my performance).

Also, it is worth noting that the tradition of tipping came from a desire to secure exemplary services. Personally, I consider it quite ethical to not tip if the service is subpar and I will tip generously if it is better than I expected.