Agreed.  I've seen how badly some treat those in service jobs. :-(   Whistling at them, snapping at them, treating them like servants or even slaves rather than human beings.

Only time I ever whistled at a server was when I'd lost my voice and was trying to order, I get that from time to time when my allergies to particularly nuts.   She told me to whistle and wave my hand if I needed her, she was very kind.