Here’s why full service went away, because after the 50s it rapidly degraded until the 70s and 80s, this is what you got:
“The attendant speedily scratched the hell out of the windshield, put in the wrong fluids, lowered the tire pressure, and spilled gasoline all over the side of the car all while charging a premium price for it.”
In short, decline in customer service.
Darn. You popped my fantasy bubble of what it would be like to have that kind of service. Now I will never think of it the same. Instead of smiling musical service station attendants in my fantasy I now see crazed car killing clowns.