The volume you are exposed to depends on how close to the speakers you are. In a large venue the people closest are getting a lot more sound than the people in the back
I think it's more than what you've described. I think it's that a lot of folks actually prefer dangerously loud volumes, and this contributes to a positive feedback loop of expectations for loud concerts. I wish most concerts were quieter, but I may be in a minority.
Anyway, the solution for "it's quiet at the back" isn't "turn it up at the front". It's line arrays, distributed speakers etc.