A similar instance with the workboat, which I'm sure many of you have seen, is a resource that is outside the cities Fat cross. Your own build list will continue to list the Wboat even though you will get no direct benefit from sending 1 to that resource tile. The tile is In your area of Influence but if you send the Wboat and it *nets* the fishies you don't get any benefit from it. Why waste the time and effort to send the wboat there? The AI will do it too.
Even if the resource is half a world away but in your area of Influence ALL your cities will list Wboat in the build list. So if I build one in China and set it on Auto it will travel if possible to New York to claim that resource that you will get no benefit from. That seems futile to me.
JosEPh
If a resource is within your cultural borders, you DO get direct health or happiness benefit; it doesn't have to be within a city's fat cross (!). I think it's coded to look for unimproved resources.
That said, I think the suggested build list may be placing too much emphasis on unimproved resources anywhere in your territory, at least in some cases like this. Then again, I never really pay attention to those list recommendations.