[SamBam]

Same reason you're allowed to gift your gold watch to someone, or sell your car.

Both of them do potentially deprive the creator of a sale, but they keep the same total number of things in circulation.

Sure, you can argue that philosophically it comes to the same thing, but the problem is that, if you win that argument, the powers that be are more likely to ban giving away things you own than they are to allow piracy...

[gosub100]

Interesting idea, but isn't the value of a book derived from the entertainment or reference usage? If I enjoy a story, the transaction is complete. I paid my money, got my product, consumed it , and now I can get another. If I transfer it to someone, the content is potentially consumed twice, but only one payment was made to the author. "Can't have your cake and eat it too - except for books"