I have this issue every time I try and rent a car with Alamo and use my debit card instead of a credit card. They always want to see my return ticket for some reason. Some locations have been more difficult to work with than others, but I almost always have to explain to them how "non revving works". Luckily, the location I fly into the most knows me by now and they only check my company ID. But In San Diego I actually had to pull out a non rev pass (the kind you just fill out yourself) and fill it out in front of him with the destination listed, which made us all feel kind of stupid.