At the Safeway near our place in SOMA, the point of sale terminal displays a prompt like this one after you’ve swiped your card and entered your pin:
WOULD YOU LIKE TO DONATE TO BREAST CANCER? YES/NO
I’ve never said yes, and neither has anyone we asked. The prompt is too vague. People are nervous when dealing with their credit cards and they are unwilling to press any buttons whose import they don’t fully understand. Further, people rush through the payment flow (because of social pressure not to hold up the line, because of their annoyance at long prompts, etc.) so when you ask them to consider a vague proposition, their answer will be “no” almost every time.
Safeway should fix this by rewriting the prompt to “Would you like to donate 1$ to breast cancer research?” and then testing other numbers between 1$ and 20$. If the TOS of the club card allows it, they should also try targeting donation amounts using purchase data. I hate complaining on the internet and not doing something about it, so if you know someone connected to Safeway who might be interested in fixing this, get in touch.