Why the US Banking System Is Divided in Two Groups?

The delinquency rate on credit-card loans at all commercial banks is very low, whereas the delinquency rate on credit-card loans is high only at commercial banks other than the 100 largest banks.

The US banking system is divided in two groups: small banks accept high credit risks vs. 100 largest banks reject high credit risks.

Delinquency Rate on Credit Card Loans