If you have watched an autonomous robot competition (I am assuming you have) you know they would not be that entertaining to the average person. A geek would find that entertaining but not average joe sixpack.

And what do you think the battlebox is now? It is 1 inch thick BULLETPROOF lexan. You will see (if you watch) in the new season of Battlebots now airing some very spectacular fights near the end of the competition.

Oh, and the current audience does sign waivers and there has been audience injuries.