This comes right from Trent Reznor and he spoke the honest truth here read his thread:
NIN decides to tour this summer. We arrive at the conclusion outdoor amphitheaters are the right venue for this outing, for a variety of reasons we've throughly considered*. In the past, NIN would sell the shows in each market to local promoters, who then "buy" the show from us to sell to you. Live Nation happens to own all the amphitheaters and bought most of the local promoters - so if you want to play those venues, you're being promoted by Live Nation.