“ATM systems have all sorts of internal auditing, and they provide you with a paper record of your transaction that you can verify on the spot. If there is a discrepancy, you can immediately go into the bank and have it resolved. If your monthly statement shows transactions that you never made, you can get your bank to fix them. ATM systems also include cameras that can be used to identify criminals or to prove that a genuine customer was using the ATM. Banking systems are not anonymous, as elections are required to be. Also banks are insured for losses (and there are considerable losses at ATMs), while elections are not insured. Election systems are thus significantly more difficult to design and build than ATM systems.”
http://www.verifiedvoting.org/article.php?id=5018
There’s a heck of a lot more to banking systems than ATM machines. ATMs aren’t even a fraction of the systems that process trillions of dollars a day.