I agree. I have a customer who is an event management firm and the complexity and size of their events (long running events that last over several days) makes the operational side of running the event the biggest challenge.
In a lot of ways it's tricky, but easy at the same time. We end up trying to build strong concepts that can be mapped onto a few different problems within the event. A lot like an online store product, but with a better grounding in events.
We then try and provide the right management/reporting/organising tools so that they can work with it better.
I have a customer I have built lots of 'back-office' functionality for into a custom event management system. T-Shirts are a simple example, each participant in their event gets a shirt (lots of races do this as well) and they have to coordinate the ordering and production of thousands of shirts, allocate the orders for pickup and ensure that it alls happens in a short amount of time. They need a structure for that process and they expect a simple integration with their registration system. To them this means that when a person or group registers they define the sizes for their people. They have rules about shirt types (kids get t-shirts and adults get collared golf shirts) and upcharges based on sizes larger than XL. This seems like a simple problem but do that 25 times for various operational aspects of their event and now you understand what is meant by 'back-office'