A strange coming together of topics

From Powell’s “funny books” display:
At first I thought it was tax tips for chefs or restaurant owners and that made sense to me. But then I read on and found that either the Tax Department has a division of Retarded and Developmentally Disabled workers who created this guide, OR the Tax Department’s Employees (not retarded) made this guide for the Retarded and Developmentally Disabled. But then I’m not sure where the culinary part comes in. Maybe the RDD people work in kitchens? Maybe the Tax Department’s employees are spicing up the title with a fun word like culinary? Like many, many things in life, I will never know the answer.