Plumbing can be a racket. I had a case in which the plumbers were supposed to up-charge and defraud customers. There are many instances of commissions in the plumbing industry.
If a plumber decides he does not want to defraud customers and is fired for refusing to make misrepresentations to customers or engage in unfair and deceptive trade practices, such as changing this 19 gallon electric gas heater for $999, and is fired for that there is a case of wrongful termination.
Yes, I actually got a quote from a plumbing company I was going to pass off $25,000 in development work to. They wanted $999 for replacing this less than $400 water heater. The average time to change out a heater like this; less than 1 hour. No plumber is worth more than $600 per hour!