Think of it like coupons vs. promotional gift cards given out by a grocery store. They use coupons in a situation where they want to encourage you to do something (buy X product), but want to limit the cost to themselves—the maximum discount is 100%. This is analogous to a non-refundable credit.

With a gift card giveaway, they’re saying the situation is such that they want to give you more money to spend, because that’d be better for everyone. This would be analogous to a refundable tax credit, which is mostly aimed a people with lower income, because helping them make ends meet and maybe even have a little extra to spend is better for everyone in the grand scheme of things.

Also an interesting tradeoff between efficient protection and redundancy. E.g. if we had eyes on all our fingers we’d probably be ok to lose a few, but also a lot more likely to lose a few.

Eyes, ears, noses, and tongues take a lot of energy to make and maintain, so having them all in one “take extra good care of this” spot is a pretty good strategy.