Why can't mechanics and dealerships never find anything wrong with your car when it's under warranty?

Update: I've read the first 9 answers and I want you to know that I take very good care of the SUV..impeccable inside/outside.. don't abuse it.. I do find that when I'm explaining the problem, the guys look at me like.. "What does not tracking right mean?".. I'm not a mechanic, so I struggle... show more I've read the first 9 answers and I want you to know that I take very good care of the SUV..impeccable inside/outside.. don't abuse it.. I do find that when I'm explaining the problem, the guys look at me like.. "What does not tracking right mean?"..
I'm not a mechanic, so I struggle with the words to best describe the problem..
Last time I took the thing in for a "rattle sound" coming from a vent.. they told me..I swear to you.."a rattle?".. "rattles are covered until 11,000 miles (mind you I had 12,000)..now if it was another kind of noise we'd look into it" "rattles aren't covered"

Since then..I'm an idiot when I get in front of a service advisor.. I'm like... hmmm..rattles are covered, but maybe squeaks are..if I say "pull" "tap" "shimmy" "vibrate" "track" "loose" ... I wonder which of those words aren't covered... You're talking to a guy who knows and love cars. Not a mechanic but I know when something is not right..
10 answers 10