If anyone is looking for directions or information about a particular area or house, one of the best persons to be contacted is the postman dealing with the area as they are delivering mail to almost every house in the locality. They will know the name of the person in every house, where the house is located and who is likely to be at home during the day.
They also know how homes in the particular locality are identified, for example most homes are numbered sequentially in an area, Unlike couriers who keep changing in smaller courier companies or ecommerce deliveries, the postman is there in a particular locality for at least a few years, though some postmen may be transferred away or they retire after 58 or as per government regulations