A very bad analogy
Audi will have designed your mirrors and written a spec on how they should work. A contractor (or Audi) will then have made them, and the components that make them up. Same goes for every single piece of the car. Audi write the spec and either make the part, someone else makes the part or someone finds an off-the-shelf part that meets the spec.
This is not the same with PCs.
MS are demanding that you have their OS on any PC. Beyond a few very small players, you cannot buy a PC from an OEM without Windows. If I go from Dell to HP to Toshiba to Sony to Acer, I am forced to take Windows. In the car world if I hate Ford engines (say) I can buy Toyota and get a Toyota engine. You just cannot do this in the PC marketplace (business accounts are different, we're not talking about them). It is not possible to choose another vendor and body-swerve the MS Tax.
If you want to stick with the car analogy, consider the radio. There's usually a choice, heck BMW used to spec sans radio! That's the kind of choice we want and need in the PC marketplace.
You only get choice from the minor vendors (e.g Morgan in the car world). They can and will meet whatever spec you desire, but you may have to pay a higher price or suffer some inconvenience (less support, less locations, longer delivery time etc etc; not always the case though).
Dell are, IMHO, wrong not to offer the refund.
MS are IMHO wrong to force vendors to sell a PC with Windows, vendors should be allowed the "no OS".
People who bash others for wanting the FREEDOM TO CHOOSE are wrong.
The USA does not have the balls to step-up to this, so let's see the EU do what's right for consumers and ensure a fairer marketplace.
Cue the MS shills...