Do banks make money off of IOTA/IOLTA accounts

I can't get a straight answer on this. In most (all?) states, the interest earned on IOTA accounts is used to fund Legal Aid other other similar charitable programs. But are the banks themselves making money off of them, that is, more interest than they are paying out? Or, do banks just offer the IOTA accounts as a service, so that attorneys will have the operating accounts there too?