Why direct invoicing with Invoice capture?

The main challenge with indirect procurement (non-stock) is it mostly done based on a value rather than quantity. For example, a professional services firm like lawyers or architects do work overtime, normally there is an expectation the services or delivery will cost an amount overall and then invoices are presented over time as work progresses i.e. total estimated at $100,000 therefore purchase agreement for $100,000 raised. The supplier then presents an invoice for $8,900 which is matched against the purchase agreement therefore deducted against it etc. Supplier continue down on purchase agreement until work complete or agreement is exhausted.

Invoice capture is heavily used in indirect procurement as EDI and other electronic documents are usually used in direct procurement (stock purchases)

This can also be the case with physical goods. An example is gardening suppliers like earth is delivered, it was delivered by the m2, but the client wanted to track the agreement and invoices by value as the amount of earth delivered cannot really be tracked by m2 due to the variability of what was contained in trucks. 

Overall, there are a lot of business scenarios where the matching of purchase orders to invoices based upon quantity and unit costs can become very difficult to create a purchase order which allows for easy matching of an invoice.