Ridiculous. Realtors do a tremendous amount of work - furthermore, if you FISBO your home or go with a discount broker (who basically does nothing but list it), you're getting away with it only because the other party generally has a realtor, who ends up doing all the legal work (title search, home inspections, warranties, contracts, etc.) for you.
People can also do their own plumbing if they are so inclined; but plumbers still have licensing standards, generally standardized rates for an area, etc. Why isn't the government suing plumbers' associations?
Plumbers rates are standard only for union work. Otherwise a plumber (in PA, anyway) can charge whatever he pleases.