Due to publisher restrictions Promo codes are not allowed for this product

I was working on a review when I realized the post was becoming more about pricing and publishing than the book itself, so I decided to separate the rant from the review.

Simple question - why is it publishers are allowed to dictate how I spend my money online?

Really, if I can use a 30% off coupon to buy the hardcover edition of a book in-store, why the hell can't I do the same with the electronic version online? It's the same book, from the same publisher, and it's the same money, from the same wallet. I've never once walked into a Home Depot or a Future Shop and been told I can't use my coupon on that brand of hammer or that brand of computer. For that matter, even back in the days when you had to spend a certain amount to be eligible, I never had Amazon tell me I couldn't get free shipping on books from that publisher..

Yes, I've read all the explanations, and I realize that many publishers are still trying to figure out this whole eBook thing, but the reality of the matter is that such a strategy does nothing but hurt the authorsUnless we're talking one of my select few must-read-right-now authors, the reality is that when I get the "Due to publisher restrictions Promo codes are not allowed for this product" error, I just move on another book, from another author, from another publisher.

So, instead of extorting full-price for what was (in this case) an overpriced eBook, the publisher urged me instead to shop from the competition, which is sad. I may not be a financial guru or a marketing wizard, but even I know that $10.49 in the publisher's pocket is better than ZERO, even if that isn't as good for them as $14.99. From an author's standpoint, where the difference in commission/royalties on those two price points is even smaller, the idea that potential readers are being pushed away from your book must be terrifying.

Here's hoping this mess gets straightened out sooner, rather than later, and that some sanity is brought to the issue of eBook pricing. Until then, I'll just have grit my teeth at the errors, take a deep breath, search for something else . . . and spend my money elsewhere.