Do these people just assume that the resume is accurate?
How do they differentiate between experience [say... admining a machine via trivial infrequent tasks] and experience [say... admining a dozen wholy different machines in a high use environment]?
At least in California, every company I was with did phone screens. You wouldn't believe the number of people who had "years" of Unix admin experience who couldn't describe what ps does [and analagous situations with other skills].
Quite odd.