Why does grocery list making even need a separate app?

Google Keep does it for me. The checkbox system just works.

I know it's perilous to depend on a Google product, and any day now I fully expect Google to kill it but I'm going to use it until that fateful day comes

Because a grocery list was part of Englebart's influential 1968 GUI demo. And because at that time, grocery mgmt was the responsibility of a man's homemaker wife, and Englebart needed to capture her list to help with the chore. Of course being a super competent can-do highly educated technological man, Englebart put to together a team to build the Mother of All Shopping List apps.

The "perfect" solution exists it was developed by Toyota and adjusted for groceries by this guy: https://www.heitmanagement.com/blog/2014/09/kanban-for-groce...

And it involves no apps nor lists.