Credit unions have become more competitive with the nation's banks. They can open accounts for almost anyone, even businesses, write mortgage loans, and generally provide any basic banking service that for-profit banks can.
And over time, credit unions have become fiercely competitive. Their not-for-profit status allows them to operate without a goal of profitability. Their tax-free status means they don't have a huge expense that taxed, for-profit banks have to pass on to their customers. Without the need to generate a profit, or pay taxes, credit unions have a massive advantage on the banks -- an advantage that can benefit the customer.