Why Should Dealers Require OS Licenses?

gandalf_grey asks: "I just got off the phone with my local Dell Rep. She's just informed me that I cannot order my PC's without an OS pre-installed, unless I have a license for my OS. This is despite the "NO OS" option on their website. I was seriously considering sending them the GPL. I ended up just requesting Linux to save myself a minor spaz, but what business is it of Dell if I own my OS or not? Any comments on similar experiences in dealing with other bulk dealers, and OS/license requirements?" Strikes me as if I buy a machien from Dell with a "No OS" license, then I should be able to put whatever I want on it. What if someone is developing an OS and they haven't written a license yet?