Bungling robbers driven by desperation are driving up bank heist statistics - like the man who caught a taxi to hold up a bank before getting dropped off at a police station to surrender.
Bank security bosses say the spike in the number of robberies defies common sense because security measures mean robbers escape with little cash and most are caught quickly.
And although desperation appears to be driving the increase, it began before the worldwide recession, suggesting other triggers in society are responsible.
Bank staff and customers have suffered about 80 robberies each year since 2006, up from about 20 a year.
One offender was a 21-year-old who targeted two banks in Timaru before handing himself in to police.
The man typified the greatest increase in bank robbers - those who pass a note demanding cash and threatening consequences.
Westpac security boss Grant Henderson said the man caught a taxi to the National Bank and was unsuccessful extorting cash. He then got the taxi to take him to Westpac, where he got a small amount of money.
"Then he got back in the taxi and went to the police and handed himself in."
BNZ security manager Owen Loeffellechner said robbers didn't tend to be "experienced or hardened criminals".
"They may be individuals that see it as an opportunity to relieve financial stress."
Police national headquarters' Detective Superintendent Win Van der Velde said motivations for robbers arrested in the past two years included debts, alcohol dependency, no money for food "and even wanting to go back to prison".