So your going to have fun at concert but... You can't hear vocals. WTF

I have been to several concerts that were not so good. I could not hear the vocals.  How many times have you been to a big venue or even a small one and you can not hear vocals?
Now nothing against foo fighters but I saw them and another big name band at a certain venue and I could
not hear vocals. how often does this happen? I have seen local bands in small venues and could not hear their vocals. do they know what a soundcheck is? 

now not judging the quality of music but just the quality of soundcheck and I would have to say Aerosmith was the best soundcheck band I saw. The vocals were as clear as day. it was in a bigger venue. How often does this happen when vocals are not loud enough? 

I would think vocals being a bit too loud is better than not loud enough. when you go to concerts do you notice a difference in sound checks? 

have you noticed drums being too loud or one instrument too loud? I say nothing is worse than vocals not being able to be heard. Maybe the singer is not as confident in their singing.

I guess you would want lower vocals for some types of music.