The shortest leg of the journey costs the most
Thousands of kilometres are cheap. The last few are not.
Something strange happens to the economics of freight as a parcel approaches you. For most of its journey it travels in company, sharing a container, a trailer or a pallet with a great many other items heading roughly the same way, and the cost of moving it is divided across all of them. Then it reaches a local depot, and the sharing stops. From that point on, a vehicle must carry your parcel specifically to your address specifically, and no other parcel can use that stop. The cost per item stops falling and starts climbing sharply.
The reason is that the last leg is dominated by stopping, not by driving. Fuel and distance are small next to the time it takes to park, find the right entrance, walk to the door, wait, scan and return to the vehicle. Density is everything: a street where twenty parcels go to twenty doors within a short walk is efficient, while a scattered rural run with long gaps between stops is not, even though the distances involved might be comparable. That is why delivery to a dense area is close to free and delivery to an isolated one is expensive, and why collection points exist at all.
It also explains why the last leg is where every clever idea in logistics gets tried. Lockers, pickup counters, neighbour drop offs, consolidated weekly runs and choose your own day options are all attempts to convert an expensive one to one movement back into a cheap shared one. None of them are really about speed, whatever the marketing around them says. They are about restoring the density that the final stretch destroys, by persuading many parcels to end their journey in the same place, or by letting the vehicle plan a route without needing to satisfy anybody in particular.