Your assessment of the ridiculous volume levels of these concerts, especially in the larger venues, couldn't be more accurate and that, ultimately, is the responsibility of the person on the mixing board(Perhaps THX should certify them, first). It would seem no matter the genre of music the rule of thumb seems to be loud and louder with bass levels, from my concert experience, acting like a defibulator on my chest. With few exceptions, I never go to concerts anymore.
I believe the issue has more to do with the acoustics, especially arenas and stadiums which are usually awful and how does THX deal with that? I remember asking a guy who mixed these live concerts, "how do you deal with the bad acoustics, echoes, etc.?" His answer? Turn it up louder!