Not a thing.
Did the truck not drive on Pennsylvania roads during delivery?
Roads that are already paid for by the trucking license fees and gasoline taxes.
Did they come by the Postal System?
Since when do the states have the authority to tax federal government agencies (or pseudo agencies in this case)?
Did Pennsylvanians handle the boxes at all?
Any tax on this labor (assuming for the moment that it should be taxed) would show up in the income tax on those laborers wages.
You see Pennsylvania DEFINITELY had something to do with the process.
PA had nothing to do with it. She bought them out of state just as surely as if she had driven out of state to pick themn up herself.
You make some very good points.