[Confusion]

  And it hadn’t cost me a dime, merely the willingness to indicate that I
  would tip for service.

This is an interesting line, because it indicates the author redefined, in his mind, what he was doing: he wasn't bribing anyone, he was merely tipping beforehand. Suddenly, the practice seems much more acceptable, to the point where I wonder why I'm instinctively against it.

I guess the answer is that we should consider a stark difference between bribing someone for 'services' that aren't at his discretion to provide, such as a police officer dropping a bill or a government employee granting a permit, versus bribing someone for services that really are at the discretion of the person being bribed. The rules for being seated at these restaurants are informal rules and no laws are broken in bending them a bit.

As a result of this article, I feel much less unfavorably about 'bribing' random personnel of companies. I wonder how long that will last.