In 80s, the Fed passed an anti-money laundering law called Chapter Title 31.The law requires all businesses that deal with cash transaction of $10.000. or more to report the customer's SS#, DOB, physical address, including height,weight, eye and hair colors. The key word here is cash transaction.
When one withdraw or deposit CASH of $10k or more , the bank is required to report to IRS without that person's knowledge.
The same apply to people buying car,boat,etc. or even gambling in casinos w/ cash of $10k or more!
Some car dealers may be trained to get all those private info even the transaction is under $10k cash, just to be on the safe side.
The fine is $25,000. minimum per violation!, the MGM Grand casino in las Vagas was fined over million dollars a few years ago for failing to report hundreds of transactions (players wagers over $10k in cash)due to the person or clerk that did the reports was so behind the work load and chose to ignore a few months reports and got caught.
After the 9/11 incident,the Fed and IRS step up audits and enforcement to work w/ Homeland Security.
Google "Title 31", and see a lot more.