Where does money come from?

This joke was apparently part of a cartoon that appeared in Accountancy many years ago.

A man, clearly to be viewed as an accountant, is standing in front of an ATM, withdrawing cash. With him are two boys.

On seeing the cash being withdrawn from the ATM, one boy turns to the other and says,

"There - I told you money doesn't grow on trees!"

With thanks to Clive Browne of Browne And Green accountants