This trust type is legal, and I have clients using them that also have bank accounts. The site you reference (the IRS site) does not say that these trusts are illegal, and specifically detail that there are several types of entities that can be used for illegal activities... none are exempt from abuse for tax evasion... LLC's corporations, partnerships as well as unincoporated business trusts. Because a customer uses a UBTO should not immediately cause you to be suspicious. One benefit of a business trust is that they are unincorporated, and as such, are not required to file with the state. In California, for example, this leads to an annual savings of $800 (the cost of the annual report required by the state). UBTO's are also used for asset protection and estate planning, and again are completely legal (and also recognized) to do so. Remember, all entities can be used for illegal activities, it's the individual behind the entity that creates the abuse, not the entity itself.
However, your customer's Trust statement regarding the Privacy Act does not exempt them from your CIP program, or any other Act of Congress that your institution is subject to. If the individual that is opening the account is a U.S. person, then they are required by the Patriot Act to disclose their SSN.
Business trusts were very popular the beginning of last century, and some laywers continue to work with them today. They are fantastic instruments in certain situations, and I wholeheartedly endorse their use for specific actvities.
I hope that this clears up some misconceptions about UBTO's. Feel free to visit our website if you have more questions:
www.trustarchitects.com (we are estate planners and managers).