The reason this philosophy is misguided is not that candidates flat out lie all the time (though that happens too), but more that resumes are crafted to inflate, exaggerate and obfuscate to make the candidate seem more qualified than they might actually be for the position upon closer scrutiny. I say I have 20 years of experience in X, but 4 of those years were just hobby projects in high school, 4 studying in university, another 5 in entry-level positions in a semi-related industry, etc etc. It would be a huge waste of time in obviously unnecessary hirings+firings to blindly trust stated experience on a resume without verifying its accuracy first.