What is the incentive to divulge the information if they don't have to? Customer service? "We're the one bank that will tell you why we are dropping you as a customer"?
Probably some amount of customer service. Banks are at their distrection then on whether they want to tell you or not -- just like for any other reason for dropping you as a customer.
I guess more important than empirically whether banks tell you, it's that it should be their right to tell you if they want.
