This is true for college textbooks. Not so for K-12 textbooks.
In this space, wholesale churn is rampant. Math series only have a several year shelf life, before old-and-broken is replaced with new-hotness. My wife and mother and sisters are all elementary school teachers, and they haven't ever stayed with a math series for more than 5 years. In our district, they are required to change them every 7.
K-12 level mathematics, compared to college level curricula, is much more "how" to teach than "what" to teach, and much more subjective. There were knock-down drag-out fights about the use of math manipulatives (which is the use of physical elements to show arithmetic operations).
Because the publishers could choose to be competent and reform their industry, but are instead eating their own seed corn. Outsourcing your technical expertise to lowest bidders in the third world is suicide in any business.
In this space, wholesale churn is rampant. Math series only have a several year shelf life, before old-and-broken is replaced with new-hotness. My wife and mother and sisters are all elementary school teachers, and they haven't ever stayed with a math series for more than 5 years. In our district, they are required to change them every 7.
K-12 level mathematics, compared to college level curricula, is much more "how" to teach than "what" to teach, and much more subjective. There were knock-down drag-out fights about the use of math manipulatives (which is the use of physical elements to show arithmetic operations).