I'm not sure what a "US International Arrival or Departure Tax" is - I'm not aware of there being anything like that, other than the 3 federal inspection fees that you list separately.

One thing that comes to mind is that the US gov't may consider the IB fuel surcharge as "fare" since it's not a gov't imposed fee. So, this may make the entire itinerary a paid ticket instead of an award ticket as far as taxes go, and might trigger additional taxes that are waived for award travel.