I thought the same thing - the way the problem is stated doesn't explicitly discount the distance walked before reaching any of the elevators, so logically the

I thought the same thing - the way the problem is stated doesn't explicitly discount the distance walked before reaching any of the elevators, so logically the answer will depend on the configuration of the lobby and where you first enter it...or at least the position of the elevator call button. E.g. if the call button is to the left of all 3 elevators, it definitely makes sense to walk to the first of those, but any further is adding distance that will be doubled if that leftmost elevator is the first to arrive. I'm pretty sure even if the next two elevators are 100s of metres away, the mean distance walked from the moment you press the call button will go up if you start walking towards them, but haven't tried proving it.