Why do most bank robbers get caught?

I've wondered why so many (including America's best) bank robbers have been caught? Bruce Allen Hughes aka The Crown Royal Bandit robbed 29 banks from 1997 to 2008, getting away with more than $300,000.00. Scott Scurlock robbed banks for four years getting away with just over $2,000,000.00. It's true that the more bank robbers keep hitting banks, the more likely they'll get caught. But what if they know when to stop. Could they still get away? And why do alot of bank robbers give tellars written notes?