Look at how ridiculous the issue is: A store can get my signature for a $5 credit card purchase, but Apple has a contract without showing it, and without getting any tangible consent?
First, it is quite common that a contract is formed without anything written and without the parties even knowing who they are dealing with. I go the the next shop and hand over some money for a newspaper: I just entered into a sales contract with a shop owner who is completely unknown to me, and the shop owner (or whoever is the legally responsible person) has entered into a sales contract with me.
The contract is entered when both sides have presented what they want, agreed on the terms, and done the necessary step to turn that agreement into a contract. In the case of the newspaper, the shop owner wants to sell newspapers for money, I want to buy a newspaper for money, we agree (the shopkeeper shows agreement by putting the newspaper with a price tag on his shelves, I show agreement by handing over the money), and the exchange of money closes the deal.
In the case of MacOS X, Apple wants to sell you a DVD and the right to use the software under its license terms. You want to install MacOS X on a computer, most likely a Mac, but perhaps some other computers. Both sides show some intent to enter into a contract by the fact that you walk away with a box, but Apple hasn't yet accepted the contract, and neither have you. Apple wants you to accept a license first, which you haven't even seen yet, so clearly there is no contract yet. You may not have noticed that Apple wants you to accept the license, but that doesn't change the fact (this is legally fine unless a company tries to sneak in terms in a way that you don't notice; you can't really miss Apple's license because the installer will display it).
At some point you are presented with the license. At that point you have a few choices. You can disagree with the license, and that means there is no contract. You and Apple should work together to undo the effect of the actions that already happened: You should return the software, Apple should refund the money. Or you can agree with the license, "tangible consent" is created when you click on an "I agree" button and the software is installed. Or you can decide that you want different contract terms. You can contact Apple and ask for a license that allows installation on your netbook. You might offer more money for such a license. I suspect Apple will reject your offer, so no contract will be entered.
But anyway, a contract is entered without Apple knowing who you are, and without Apple having anything in writing that you entered the contract. That should be fine; you know who Apple is, and you have the contract terms in writing, so if there was a legal argument you could always prove the terms of the contract. Apple might not be able to proof that you entered the contract, but they seem to be fine with that (either there was no contract, in which case you didn't have the right to install their software anywhere, or there was a contract, and you only had the right to install the software according to the license).
So assuming that Apple does not accept any offers for a different contract, there is indeed a valid contract if you paid for the software and accepted Apple's license, even though there is no signed contract and Apple doesn't even know who you are. There is nothing unusual about that.
Now think what would be the alternative: Do you think Apple should show you the license terms and sign a contract when you buy MacOS X? What is better for you as a customer: Having to read the license in a crowded Apple Store, with your wife pointing to her watch, putting you under pressure to make your decision quicker, or you don't have your reading glasses with you, so you have to come back later, or being able to read the license later at your home, where you can take as much time as you like to examine it, no sales people in your neck? All this "show me the license and make me sign a contract" is really nice for having an argument on the Internet, but in practice it would be just a major pain in the behind.
UCC law applies to the media, and Copyright law gives me rights to the the intellectual property content on the media. I think that is what you are missing.(I have rights under Copyright law, not just Apple.)
Each exists without the presence of a license contract between the buyer and Apple Inc. The license contract attempts to take away rights I would have had under UCC and Copyright law. Usually, it takes a signed waiver to give up rights. You would have us believe that I lose my rights over a contract that is not shown at the checkout stand, and which I haven't signed.
You don't have any rights to anything until you enter into some contract with Apple. You will then have exactly the rights that the contract gives you. You _want_ a contract that says (I'm assuming) "I hand over cash to Apple, Apple gives me a DVD with MacOS X, and the right to install the software on a computer of my choice, and some reasonable additional rights like making a backup and loading the software into RAM to execute it". Unfortunately for you, that is not a contract that Apple is willing to accept. They offer a contract that you don't like. You can accept, decline, or make a different offer. If you accept the contract offer, you don't get all the rights that you wanted, but you don't lose any rights, because without the contract, you had no rights at all.
It doesn't matter that you didn't know the exact terms of the contract at the checkout stand, because nobody asked you to accept the contract at that point, and you didn't enter into a contract at that point. At the point you enter the contract, you know the terms (or you were too lazy or too trusting to read them). You enter the contract. The fact that you don't sign anything means you may be able to deny entering the contract if you feel that is beneficial for you.
And the signature under a contract doesn't make the contract more valid (except when you have a contract that says "only valid if both parties signed here"), it only means that it is easier for the sides to _prove_ that a contract was entered. If Apple said "you owe us your first-born child because the MacOS X license says so", you could just turn around and tell them that they cannot prove that there is any contract between you because you signed nothing. If Apple said "you were infringing on our copyrights by using the software without accepting the license" you can just turn around and tell them they cannot prove that you didn't enter the contract by accepting the license, because they didn't ask for a signature.
Obviously, without a contract you don't have any rights to the software at all.