Question about French Chamber of Commerce

Its description say “all of the player’s Traders and Trade Ships to return 30% more resources to any Market or Dock”, but it practice, it doesn’t seem to affect the amount generate by Traders while other resources do increase by 30%. Is it a bug or working as intended? If it’s intended, it would make that Landmark a lot less valuable. I’m not saying it’s not useful as infinite wood and stone is still good but the resource I most desire from Traders is still gold