When I worked for Hertz, I went to a higher up in the rental department, and told him that the brakes on some of the cars we were getting in the sales end of thigs, had dangerously thin brake pads. He first asked me if they were "within spec". I asked what that would be and he said he didn't know. I then told him that a car that had ~ 1mm of pad remaining would be a gold mine for an ambulance chasing attorney, if they were found on a rental car. I also brought a Ford Focus, that had literally over 100 pounds of air in each tire. He said, "is that too much"? I didn't even know where to begin.
He said to forget about it, and that "we've been doing things like that for years, and never had a problem". So, as you can see, most rental car companies promote from within, and it's not always the most qualified for the position.