http://www.finra.org/Industry/Issues/AML/
http://answers.yahoo.com/question/index?qid=20090205191027AAOr0jC
You’re right, due to Anti-Money Laundering, Know Your Customer and Patriot Act rules banks are forced into some pretty stringent reporting when it comes to cashing checks and depositing/transferring/withdrawing money.
The ATM restrictions are there so the machines don’t run out of money too quick and if the withdrawal is large enough certain paperwork must be filled out and the customer must provide verifiable information (Patriot Act). The limit is also dependent on what type of customer you are, usually calculated by a score that takes into account your total relationship with the bank, deposits, activities, etc. Most people get a standard $500 limit, others might have $1000/1500 or even $250.
Trust me, I work in technology at a bank and have to take a test every year! We have systems upon systems to handle/report due to these government restrictions.
Oh, don’t ask a teller or other branch worker, rules and regulations disallow them from talking to you about everything they have to do. Wait until Dodd/Frank is fully implemented...
The technology that is involved to meet regulations is amazing, and still it can't prevent a lot of things.