The need to cash checks, money orders, to get official checks, to get change, to send wires to family out of the country. This is an access system for people who don't have savings or checking accounts, that is, people who don't have enough net income to have savings. There are two common bank models of pricing for this level of services. Banks forgo charges for these types of transactions on the basis of compensating balances. This, in effect, denies reasonable access.
Check cashing outlets use predatory pricing, making transactions overly expensive.
We price these services to reflect who we expect to buy them. We also price the service to make money for the Credit Union. We're trying to encourage ourselves to develop profitable services for this niche. Small savings account is something Credit Unions have been in a long time. To make this work we have to pay interest on these accounts.