I'm laughing because there's not much chance of me using one either. But I have several reasons.
1. After 42 years of marriage can DH pick out fresh fruits, vegetables and meat to my satisfaction. There's a miniscule chance that some random person will do it to my standards.
2. I don't think I've ever made a completely comprehensive grocery list in all the years we've been married. Years ago DH learned about my grocery lists. He came home with everything on the list and not one other thing! I was stunned that he never realized my lists only consist of the things I want to make sure I don't forget. What we're out of or about out of, the sale items I want and things I need for the meals I've planned. How can I know everything I'll want until I get there and see what they have?
3. The chances of me going into a grocery store, even when we only need one or two things, and not doing every aisle but the laundry, cleaning and paper product aisles? Good luck with that! I sometimes wait in the car while DH goes in when we just need a couple of things because he can go in, get them, pay and be back to the car in under 10 minutes.