I was once interviewed for a USG background check. I was not named by the subject and there definitely is a policy that such people are important. But the investigator got my name from one of the named references, whom the investigator did interview. (The person who gave my name told me these details and furthermore said that there was a frantic search for someone else to interview that day so that the investigator did not have to make a second trip.)
Over the past couple of decades, I've sent out a few hundred resumes (maybe, I don't know, 300 or 400--my spreadsheet for 2013-2015 lists 145 applications). Out of those I've gotten at most two dozen interviews and a dozen job offers.
Throughout that time I've maintained a list of references on my resume. The rest of the resume is, to my mind, not very informative. The list of job titles and degrees says little about how competent I was.
Now and then, I check with one of my references to see if anyone called them. I checked again yesterday with the second reference on my list. The answer was the same: Nope. No one has ever, as far as I can recall, called any of my references. Not the people who interviewed me; not the people who offered me jobs.
When the US government did a background check on me, they asked me for a list of references to contact. My uncertain recollection is that they ignored it and interviewed my neighbors and other contacts instead, as if what I had given them was a list of people not to bother contacting because they'd only say good things about me.
Is this rational or irrational? Why does every employer ask for a list of references, then not call them?