Let's see if I get this right.
If I go to a town, I have two options:
OPTION A: Scroll around their town searching for a building with a gift box, which gives me a benefit but not them. (Assuming they have available buildings at the moment)
OR
OPTION B: Tap the Federal Elf Detection Service button, which is always available in the same spot on my screen, once I get to the quest point, which benefits me EXACTLY as Option A, PLUS I am helping them.
Also, in contrast to gremaliens, I never run out of Feds. I can help Every. Single. Neighbor. From A-to-Z, long after I stop getting gift boxes myself.
Did I miss something? As suetopia asked, is there a DISadvantage to it? (Option B). Why would anyone NOT do it?