What's the deal with 12-15K oil changes?

[cinellipro]

We change our oil at about 3-5000 miles. MINI and BMW, and a few others require oil changes at 12-15,000 miles. When did oil manufacturing become so improved that we can start changing oil at 12-12K miles? If so then why hasn't every auto maker shifted the scheduled oil changes to 8 or 10 or 12K miles?
A friend mentioned that the extended oil change recommendation is a marketing scheme originally created by the "scheduled maintenance included" crowd and has nothing to do with the oil quality. She states that it was an algrorithm calculated which included the following variables; average length of time and miles a typical owner keeps their car and the length of the factory warranty. Once a car has reached that terminal mileage or time where the extended oil changes would incur damage on the engine, the car is in the hands of a second unwarranteed owner.
Just a thought.
Happy Driving