Absolutely none of that explains why they can't refund you the cost of the license if you wipe the drive.
Duh, it's because it's a pain in the ass and only about 17 people in the whole freaking country would want to do so and get the refund. PC manufacturers have no obligation to set up a special process to attend to the desires of the vanishingly small % of the population that wants a bare metal PC. For the segment that actually has a significant number of users that want bare metal machines, the server market, there are plenty of machines available. See my favorite white box provider, here for an example.
It's not free for a company to process refunds. Companies have clearly decided there is no money in offering bare metal machines. The segment of the market that actually cares about not paying the windows tax is small enough that it can be ignored. If it wasn't, you'd be able to buy bare metal machines, because someone would think they can make money doing so.
Sorry, but it's just a reality that there aren't that many people who care about this issue.