What's the problem with selling older cookbooks?

I took a load of books to the Recycle Bookstore yesterday, a cross section or sampling to see what they might like to get more of. I really thought all the things I took were pretty juicy, but the buyer didn’t take very much.

One of the things he brushed aside was a large, well-illustrated, comprehensive volume of Asian cooking across many nations, ethnicities, and cultures. He said there’s not much interest in older cookbooks.

I thought cookbooks had a use life of centuries! I thought they were practically immortal in used bookstores. This Asian collection was published in 1976, and I bought this edition in 1990. How can recipes grow obsolete? I can’t imagine that anything in there couldn’t be cooked now, to great success.

What’s the deal with older cookbooks, do you know?