There is a distinction with respect to a bank or financial institution being a member of an FRB and holding an account at an FRB (i.e. these are clearinghouse accounts for settlement and netting). Credit unions and state banks afaik might hold accounts with an FRB without being a 'member bank'. All national banking associations are required to become FRB members AFAIK.
Related: What is the advantage of putting your money in a Fed member bank versus a bank that is a nonmember? How do you know which banks are Fed members? (Federal Reserve Bank of San Francisco).
U.S. Bank N.A. is a national banking association chartered under the Office of the Comptroller of the Currency of the U.S. Credit unions, however are typically State chartered financial institutions. Perhaps the aspect of holding stock in an FRB brings with it an encouragement to maximize the profits by feeding off of as many clueless customers as possible? With credit unions and state banks being non-members and non-stock-holders perhaps they could care less--all an FRB might be for them is a clearinghouse rather than a potential profit source.National banks chartered by the federal government are, by law, members of the Federal Reserve System. State-chartered banks may choose to become members of the Federal Reserve System if they meet the standards set by the Board of Governors. Each member bank is required to subscribe to stock in its regional Federal Reserve Bank, but holding Federal Reserve stock is not like holding publicly traded stock. Reserve Bank stock cannot be sold, traded, or pledged as collateral for loans. As specified by law, member banks receive a six percent annual dividend on their Federal Reserve Bank stock; member banks also vote for Class A and Class B directors of the Reserve Bank.
It could also be that state banks and credit unions might tend to face more staunch troubles for usury than a nationally associated bank might.We (brain trust) have noticed that credit unions have much less concern about non-endorsement. I did not consider why carefully until you gave me some details.