Arenas and stadiums never have sound systems appropriate for a rock band - they always tour with their own rigs. But for many other events, like the circus or tractor pulls or stand-up comics, they will use what's installed. The installed systems were never designed to achieve SPL's most band require. Not to mention the familiarity with using the same rig night after night.
The only thing touring acts used in the Saddledome (30 years ago) was our Clearcom system, which is a hardwired headset system that allowed the LD to talk to the followspot operators in the rafters. They may use their own wireless systems in this day and age.
[edited] The previous roof of stadium out here, Canada Place, was inflated. For huge flown rigs like the one Pink Floyd used, they would turn on extra fans to keep the roof inflated enough. The extra fans were installed for just such a purpose.