The walls do look like mostly if not entirely new construction - i never claimed they never made new stuff. I said there's some ghetto pieces that get reused way too often.
Floor is reused - which you didn't notice. And that's not the "actual ground." It's reused and has sections where it's obviously been replaced.
Basic schmatic of fake-walls:
http://www.dolphin.upenn.edu/pacshop/Images/flat-rear.png
Any of those bits can be reused. Any notice how in your photos it's all bare plywood. They get covered with finishes. We know more a fact that most of what we see in HHN on those is black - basic flat black. Even if you paint it black, plywood will look like crap. So those aren't skinned (save for those railings on the slope and the pillar looking thingy). Take the skin off and it looks like brand new wood unless it's particularly ghetto.
Which i didn't bother to take photos of and Aiello knows better than to do so himself either, but they exist and are reused year to year.