They were until now. They're not anymore because people paid 70ish to see Fleetwood Mac, U2, AC/DC, Beyonce, Madonna, Springsteen, Paul Simon, Sting, Eagles, Stones, Macca, Elton, Adele, etc on their tours.
60 ish was the standard on their tours before that. Itll cost 100+ next time around because all the current crop are selling out their gigs.
Simple really. If the demand is huge the price goes up. No one to blame but ourselves.
They really are. Considering theres a very good chance the sound will be shit seated in a stadium.