You really think that the Tullys don’t belong in Tier 2 or 2.5? Yes, they are not particularly industrious about building canals, roads or bridges. But that doesn’t really hamper trade as we know that during peacetimes mile long lines of poleboat form in the rivers. Their lack of cities is somewhat made up for by several prosperous towns, and the land is very fertile. As for tax collection, the riverlords might be quarrelsome, but all of them except the Freys seem to respect Tully authority.

I think it does actually hamper trade, by increasing costs and limiting where trade can flow. For example, I think it’s majorly harmed the growth of Maidenpool and Saltpans that neither of them are on the major road networks – if you’re a ship’s captain, why go to Maidenpool or Saltpans when you could go to King’s Landing instead, with all of those broad royal highways connecting?

And no, I don’t think the towns make up for the lack of cities – city charters are enormously important. It’s not just a matter of convenience, legally you can’t have proper markets or warehouses without a charter saying you can. 

As for tax collection, it’s not just the Freys. It’s also the Brackens and Blackwoods who the Tullys aren’t capable of restraining. It’s also the fact that the Tullys seem capable of raising only 20,000 men maximum, when the size and fertility of the Riverlands would suggest they ought to be able to raise twice that many.