Yep, trusting every submission initially is fine, and we do use tricks like you suggest to flag suspicious accounts. For instance if you submit "11111" then "11

Yep, trusting every submission initially is fine, and we do use tricks like you suggest to flag suspicious accounts. For instance if you submit "11111" then "11112" then "11113" on up through "99999" (I've seen it happen!) then we might disqualify you from the raffle. :-) (We have better heuristics than that too.) But having the phone send some kind of extra proof would still be helpful. To point is just to make location spoofing "hard enough," not impossible. Also it is a small enough event that fraud isn't a true problem right now, so this is more just a fun mental exercise for me at this point. Still, good to be prepared!