[alexvoda]

Than you agree and are missing the point.

Some textbook publishers are intentionally making small changes from year to year to intentionally make the life of those using second hand text books miserable.

Corporations have long since realised that often their biggest competition comes from their own products therefore we now have planned obsolescence (someone who already has your product and doesn't want to buy another) and the war on secondary markets (someone other than you selling your, old, product).