Airport rental agencies charge the highest rates of all. Maybe because the cars are frightened of the planes flying close overhead! One can usually do better by taking a cab or Uber to a rental agency in another part of town.

As a general rule, however - rates are in part based upon a risk factor - maybe lots of cars are damaged in accidents around Las Vegas, or abandoned or stolen, such that the agencies incur a high "recovery fee."

See if you can become a "rental car club" member which entitles one to a discount.