Back in my earliest days in the trade I worked as an Electrical Mechanic. Our Labour rates were posted as $20.00/Hr. $30.00 if you watch. $40.00 if you help.
and we pointed this out and made sure the customer did not think we were kidding because we were not. It helped a lot in keeping our costs down both from the inevitable distractions and loss of borrowed tools. Still there was always the guy who insisted on paying $40.00/ hr.