Simple. Because your "common economic logic" is neither logical nor economical. As has been noted previously, by your irrational assumptions Wal-Mart bases its largest distributership out of Bentonville, Arkansas because that is where most of the consumers live. Granted, while there may be a lot of trailer parks to consume cheap retail crap in Bentonville, it is absurd to believe that a rural town in the middle of nowhere outconsumes the rest of the nation.
The Warehousing Act encouraged importers to drop their goods off at a single point by providing economic incentives to warehouse. Specifically, an importer could delay payment on the tariff until he had a buyer for his goods by storing them tax-free in a warehouse. Since NYC had lots of warehouses to be used for this purpose it became the dropoff place for goods that were later reexported to buyers elsewhere in the country.
And by your logic are we to assume that each and every product Walmart sells passes through Bentonville?
Specifically, an importer could delay payment on the tariff until he had a buyer for his goods by storing them tax-free in a warehouse.
Read the legislation.