I agree with you. I like using Dollar - better value than the other companies, and with my express membership I can go right to the key kiosk in the parking lot instead of standing in line with the tourists for an hour at the airport booth.
That code really helped to keep the rate acceptable to my company. They want me to go with the lowest rate and when Enterprise was at $80 and Dollar was at $100 for a day in SEAtac, I would use the code to get the $40 rate and stick with Dollar.