X2
They are on contract.
GS has the list of them. If you are stranded you will not get the closet tow. You will get the 'closet tow on contract to GS'.
Just any ole tow company is not going to even know who GS is and more importantly how they would get reimbursed after they service you for free if the 'don't have a contract' from that company.
Think about it. No tow truck company is going to give you free service and not know the company that is gong to pay them! :B:W
A tow company under contract performs the job for free and knows the company and has the paperwork on how to be reimbursed.