I realize this will never happen. Getting dealer owners to agree on anything is nearly impossible. Getting them to agree not to take advantage of another dealer IS impossible - like herding cats, while riding a dog.
Just think if dealerships could / would strike. Think about that for a minute and what would you ask for?
Fair warranty reimbursement of parts
Fair labor times paid to technicians
Fair treatment of dealerships relating to all things policy / procedure related
Stop charging us the highest price out there for parts - we are the only ones selling your vehicles
Stop saying "Put the customer at the center of everything you do" when most representatives couldn't care less about the customer
Here is an idea - GM actually stocks a part and ships it to the dealer - the same day it is ordered. Dealer receives next morning PRIOR to opening
Help desks should be staffed and located in the country in which they serve - speaking the local language, understand the local expectations
I could go on but what do you want?