Ditto, you have to see it from the point that we are professionals. It has nothing to do with how much we earn in comparison to other professionals (e.g. surgeons, dentists, etc). It's more about doing the job and having pride in doing it well.

While the idea naturally sounds pleasing to think about having an extra $200/wk in our pockets, it's not worth the degrading of image.

We don't tip surgeons for saving lives. It's considered an obligation for every professional to do a good job with high standards. Taxi drivers, waiters, etc, while they SHOULD provide good service because, in the end, that IS the job they signed up for, don't have any obligation to please you but more like meeting the requirements of the business who they work for. The tip is only an incentive for them to cater to you, the individual.