Due to the urban canyon effect with limited visibility to overhead navigation satellites, lat/long doesn't necessarily have enough precision for reliable delivery. Are you supposed to deliver the package here or to the building next door? With street address numbers it's easy to verify but with only lat/long it's hard to be certain.

The Japanese Quasi-Zenith Satellite System (QZSS) is designed specifically to work around this problem, but that level of precision isn't available everywhere yet.