Suppose I need cash. Suppose I also need groceries. I go grocery shopping, and when it comes time to check out I also use that neat cash back thing, where I "spend" $20 off my debit card, and get $20 in cash immediately.
This answer lists some pros and cons of doing so, but the only cons mentioned relate to cash itself (i.e. I can lose it, there may not be a record of my purchases, etc.). My question is this; what are the disadvantages of using the cash back option at grocery stores besides those inherent in cash?