I voted to reopen the below question. Here's my reasoning:

- It is regarding the Magento admin panel reports
- It asks why a report behaves a certain way
- It can have a single, canonical answer

Because of the above I feel that it fits well into the format of this site. If it were asked *why the developers chose* to make it work a certain way it would be off-topic, the question is asking how to extend the report. I will attempt to answer myself.

In the meantime any thoughts from the community on why this may or may not belong? 

https://magento.stackexchange.com/questions/82033/customers-by-orders-total-only-shows-5