(1) The passage quoted about planetary and interstellar and in-system transport costs does not equate them to one another, nor does it assert anywhere that they do not add to one another when it comes to calculating the total end-to-end cost of moving something.
(2) Planetary and atmospheric transport from the passage quoted does not and never did refer to the least possible theoretical cost of planetary or atmospheric shipping. It refers to the actual cost per ton of the way goods are shipped, and it assumes distribution from/to nodal positions on a planetary surface, period.
(3) I never said that it wasn't possible to ship goods cheaply in atmosphere or from point-to-point. What I said was that the cost of interplanetary and interstellar shipping is lower than the actual cost --- that is, the way planetary and atmospheric shipping logistics actually work in the Honorverse --- of shipping those goods in a planetary environment, and it is. This results --- I repeat one more time --- because of the difference in scale.
(4) People simply don't ship five-million-ton lots of goods in planetary and atmospheric environments. Not because they couldn't but because, by and large, there is no need to, anymore than there is a need to deliver 5,000,000-tons of tires simultaneously to a single Wall Mart location in Houston, Texas. Goods are shipped in much smaller quantities, and in the Honorverse, the cost of shipping 5 tons is closely approximate to the cost of shipping 5 million tons. This means --- pay attention closely now, this is really complicated

(5) At no point have I ever said that planetary/atmospheric transport costs were not a factor in interstellar or interplanetary commerce. Once a 5,000,000 ton shipment reaches its destination, it has to be delivered to the surface of the planet (or the internal systems of an orbital habitat, or whatever) where it manifestly (i.e., I thought it was so damned obvious there was no need to point this out to anyone with functioning neurons) enters the local distribution system and incurs whatever transportation costs purely local goods would incur in addition to the interplanetary or interstellar transportation costs. My entire point in the quoted passage --- and every single other place I have addressed this issue --- is that on a ton-for-ton basis, the interplanetary and/or interstellar portion of the trip costs less than the planetary portion(s) of a cargo's trip. I've never said, asserted, or suggested anything more than that.
Please do me the courtesy of reading what I've actually said and not assuming that I've said something that I haven't.
And now, I'm done.