> I just don't get why these companies should be in the business of offering gift cards
If they're anything like Starbucks then they get the benefit of utilizing the unredeemed balances as temporary capital for investments. It's an interest free loan at their scale. Plus they get to keep the balance that people forget to redeem.
> Plus they get to keep the balance that people forget to redeem
I'm not an expert here, but this is not generally true. See "giftcard escheatment laws". I think these vary by state, but see e.g. https://legalclarity.org/when-do-gift-cards-become-subject-t... The value of abandoned cards goes to the state.