I travel a lot for work, to many different cities, and this is the worst rental car set up I have seen. The line for the rental car shuttle was 4 bus loads long, and the ride is at least 10 minutes from the terminal.
Upon arriving at the rental car garage, there were 10 parties waiting for a vehicle.
It is a holiday weekend, but then it needs to be staffed accordingly.
The Phoenix airport boasts, "the friendliest airport in America". They are friendly, but very inefficient.