exactly, its a unfair advantage for humans because none of them turn on the train, so zombies will have to boost (far less zombies to begin with) and if they all slapped up thered be even less ppl to turn. and zombies such as fast wont be able to jump up to those unintended spots and the only way to get to the treehouse is the train, and humans dont activate it... so zombies have to go do the human's job as well.