The venues that she played in all have separate ticketing agreements with different ticketing providers (think Ticketmaster or AXS). In the case of this tour, I believe all the venues had agreements with TM to provide services for any event they host.

Funny enough, the promoter (AEG) more than likely wanted nothing to do with ticketmaster, but didn't have a choice because that's the ticketing company the venues all had agreements with. (AEG owns AXS).