A driver leaves the depot with twenty or thirty stops on the manifest. From that moment until he calls in — if he calls in — the office has no reliable picture of what has actually been delivered. A customer phones asking where their order is, the coordinator puts them on hold, calls the driver, waits for him to pull over, and calls the customer back. Multiply that by every route, every day.
The status that matters is not where the van is. It is whether stop number fourteen was delivered, failed, or dropped as a partial — and right now that lives only in the driver's memory and a stack of paper delivery notes on the passenger seat. Nobody in the office can see it until the van comes back and someone types it up.
So the daily report is compiled after the fact. Someone collects the paper notes, cross-checks them against the manifest, chases drivers for the stops that don't reconcile, and keys the whole thing into a spreadsheet the next morning. By the time the report exists, the day it describes is over. A failed delivery you could have re-attempted at 2pm is now a re-attempt tomorrow — and an unhappy customer today.
Proof of delivery carries the same lag. A signature on paper is fine until a client disputes a drop and finance has to find the note weeks later. The information exists; it just isn't captured anywhere you can query it, and it isn't available at the moment a decision actually depends on it.