Forced 18% "Gratuity"

I'm wrapping up a business trip and when we all went out to eat last evening, the bill included a forced gratuity of 18%. First off, a gratuity is supposed to be an extra freely given for satisfactory or exceptional service. It has, however, become a way for certain businesses to get their customers to (at least partially) pay their employees. I believe the word gratuity is perhaps no longer appropriate. Maybe it should be called, Your portion of our employees wages.