Some of the most common banking trojans we run into are versions of ZeuS (ZBot) and SpyEye. These are not your average bots. They are commercially developed crimeware. The trick is that the groups that develop and sell ZeuS and SpyEye do not use them themselves.
Customers that buy ZeuS or SpyEye are the ones that actually attack the banks, and doing so, they take a higher risk of getting caught.
This is the equivalent of somebody selling instructions on how to break into banks vault, complete with the tools to do it — but not actually breaking in themselves.
Just how professional are these tools? Well, take a look at the recently leaked manual of ZeuS 2.0.8.9.
Turns out this criminal banking trojan has better documentation than most software that we see.