Customers who want an out of state drop off normally put higher then normal mileage on the car. Number of miles on the odomoter determines resale value of the car.
Frequently out of state returns will result in either a drop fee, discounts blacked out or a limited number of free miles.
Rental companies make exceptions when their computer suggests cars need to be moved from one location to another. Seasonal needs in Florida is an example.
You have to do your homework. Look at your total cost. Sometimes a drop fee will give you your lowest rate. Figure out how many miles you'll be driving. Sometimes accepting a limited number of miles gives you the best rate.
Try Kayak. Try travelocity. Frequently the coupons we normally use won't give you the best one way rate.
Last year I needed a one way rental from PHX to LAS.
Alamo gave me a good rate. I kept checking. As I got closer to my date Alamo had a drop fee. Even closer there were no cars available for a one way rental. Alamo had a limited number of cars they wanted moved to Vegas. Once they had enough reservations the terms changed.