I rode home with a co-worker a few days ago and I asked her to wait for me while I used the ATM machine. She asked if I trusted "those people".  

"People WHO?" I asked.  

She said, "The ATM people! You know how the ATM operates by having a person inside the box.  Every time you put in your card, he takes it, looks at it, and checks his paper files and folders for your account number. Here he can find your PIN and check the balance.  This person then asks you to ENTER your PIN, cross checks it, and if all matches, you can proceed. If not, he keeps your card.  

"If you ask for a statement, he types it from his books and you get the printout.  If you ask for a withdrawal, he checks the balance and any restrictions, and if all is ok, gives you the amount.  He then calls all of the other branches and ATMs, tells them how much you've withdrawn, so they can update THEIR books."