Every rental for the past year for me goes like this....

Me: Hello, I filled up the tank on the way back.

Attendent: Ok... [checks mileage and fuel level then prints receipt]... Have a nice day.

Me: [looks at receipt, no EZEFUEL on it] Thank you.

Never had an issue with this... at least not at OGG, HNL, SFO, SJC, OAK, DAY, IND, CMH, MSP, STL... those are the ones I can think of off the top of my head.