It might not actually be wasted money. We've had teachers over the years clear out samples of unadopted materials by sending them home with interested students at the end of the year. We've also gotten unused workbooks home that were sold as a package with texts that were used in class (with no option to order texts without the accompanying workbooks, or in one particularly odd case, where the texts alone would have cost more than the text/workbook package). And one year, DS had a teacher that won a grant to provide summer enrichment material for her students.
If the school paid extra for the workbooks they're obviously a waste, but that may not actually be the case.
I was going to say something similar. People outside the education system don't know the "ins and outs" of textbook adoptions, but here are a couple trends we've been seeing over the last few years:
Expensive books with freebies. This is what I suspect your son's school has. My textbooks, for example, are outrageously expensive -- they're around $70 each -- but for each English textbook my school bought, we were allowed to choose two hardcover novels, one heavy paperback play, and two consumable workbooks. We "adopt" the books from a specific publisher for a five-year timeperiod, and the publisher provides us with those consumable workbooks every year. We get to choose from a list of workbooks, which includes vocabulary, test prep books, grammar, and reader workbooks. We have the option to take some of our workbooks in Spanish, and we can choose to take some of our books in -- for lack of a better term -- super simple versions (these, of course, are for our lower-level students). Whatever we choose on our adoption year, we're going to get for the next five years -- we cannot choose vocabulary books this year and switch to writing books next year. (So if we buy 300 9th grade English textbooks, we could receive 300 grammar workbooks and 300 vocabulary workbooks every fall.)
We cannot negotiate a lower price by skipping the workbooks -- the textbooks cost the same $70 whether we take the workbooks or don't take the workbooks.
And if the teacher doesn't use the workbooks, which aren't that great, they're sitting around school taking up space. If a teacher LOVES the vocabulary books, but she leaves the school two years into the textbook adoption, well, you'd better hope that her replacement didn't want the grammar workbooks instead because they're going to be piled in her classroom every August.
I know what you're going to say: Why don't schools buy from a company that doesn't play this game? Why don't we buy from a company that JUST SELLS TEXTBOOKS and allows us to buy individual novel sets, etc.? Simple: All the big companies are doing the same things these days. They know there's profit in selling a whole package.
We also get so much teacher stuff along with the books that no one could ever go through it all, much less actually use it: Fine arts transparancies, writing starter videos, DOL (Daily Oral Language).
Speaking only for myself, I love the novels that come with the textbook. They're good quality books that hold up well, though I wish we had more modern authors from which to choose. The options we have available are largely old stuff that's copywrite free.
Another trend:
Textbook makers super-sizing their books. The page margins are getting larger, most pages include color pictures or borders, and this means less text on each page. Lengthy introductions, questions at the end of each story, multi-cultural references and biographies fill the books. The books are growing larger, yet there's less material in them.
Sadly, our children ARE conditioned to consider something "pretty" of greater value than something printed in simple black and white.
Another trend:
Textbooks on disks so that the school can just buy a CLASS SET of textbooks for each teacher's classroom, and each student gets a CD to tote home. An alternative is a code for each student to access the book online. In my experience, these things give students an excuse NOT to do their work at home: They didn't get a turn on the computer, or they couldn't access the textbook last night (my own daughter has found that her science textbook is available sometimes and not available other times; it's maddening). My other daugther is uber-paranoid about her CD disk because her teacher told her that if she loses or damages the CD or its case, it'll cost her $$$$$$$$$$. These systems need refining.