So the cleaning crew at the building where I work probably work harder and get paid less than any of them. In the end there is no point in trying to justify any of this. It all boils down to tradition.

Just for the fun of it:

If I could wave a magic wand I would eliminate tipping as a form of compensation. As part of this wand waving the inequalities that make people say “These people don’t get paid enough and they deserve tips” would also be rectified. I personally believe that, on average, tipping is not a productive for of compensation and generally does not promote better service.