They have an office full of people processing cheques, cash etc etc. In the old world, all cheques were processed by hand but in the new world, all cheques are processed by a combination of electronic imaging and MICR: people only look at the ones where tech processes fails. Which are a lot of them.
This area of finance is called "Corporate Cash Management" - a bit of misnomer because it is not just cash and is primarily electronic these days. It is essentially about the processes that need to be in place to physically and electronically move money around.
Here are some examples of what the biggest bank in Canada offers in this space.
The do not explicitly mention cheques because that space is really well automated these days but it is mostly done really well by technology and most banks are trying to move away to electronic payments. But if you ask for it, you will get it at specially quoted per customer rates.
The accountants just go "huh, this one doesn't match up with anything" later on.