[icecap12]

In my experience, this most frequently occurs if the company does business with the government (fed, state, or local). In such cases, the "charade" is required by Federal or State law. I agree its absolutely ridiculous, but large companies can and are in fact frequently audited on these and other hiring practice requirements (such as interview notes, etc.).

At my $BIGCORP, if you want to give somebody a band promotion (meaning, up to the next major band), the job must be posted both internally and externally and you must interview any candidates who appear to meet the requirements. It's a pain in the ass, especially when you clearly have someone in mind. There are always people both internal and external looking at our jobs site because we're a well known Fortune 50; you're bound to get applicants to the higher level roles. It just creates extra work and wastes the time of all involved...but alas, regulation.

eta: could also be a requirement of publicly traded companies, though I'm far less sure on this.

[chevman]

It's not so much an actual regulation, as it is good practice that once you get large enough (ie attractive enough to sue), HR will implement actions to "affirmatively demonstrate" that they are fair in their hiring practices.

[cyanydeez]

Typically, I assume most fuckery is built into a business charter and becomes so ingrained, most employees have no idea why they're jumping through the hoops