? about BOA Visa cash back card

[KNJWDW]

I am hoping someone on here can shed some light on this for me. My mother just signed up for BOA visa cash back card (power rewards, I think.) She told me that not every merchant participates in it. This confuses me, I assumed if Visa is accepted, then whatever program that is affiliated with the card applies. The only rewards card I currently use is my Disney card and I know that is good just about anywhere! So, is my mom correct in saying that she may not always be getting credit for using this card? Are there different rules for cash back cards vs. other reward cards?

Thx.

Amy