Thanks, man.  Now I know.  And, I lament that I've posted photos, many times before, only now realizing they were never seen.   Never again!
  Never again!  
okay, @dagobah, I've updated all photos in this post, now, FWIW.  Please confirm visibility, and if you're still interested, hopefully my first set of photos will still prove helpful in navigating various iTunes views, etc.
Like I wrote in my post above, I see 
all the photos in your post on page 1 of this thread.  It's a great explanation and I really appreciate it.  My iTunes Library 
is in the 
Songs View.  And I choose 
not to show artwork because, for 
me, it takes up too much space.
I want only these columns of info on my iTunes track screen (
from left to right):
Track Name,  
Track Time,  
Artist,  
Album,  
Comments,  
Number Of PlaysYes, I could 
also have a column for 
Kind, but I rarely need that info.  And since I rarely need that info, I don't want it cluttering up my iTunes screen.  But when I 
do want that info, I right-click on the track, choose 
Get Info and look at the top left of the 
Get Info box.  There will either be 
Album Artwork or . . . . . . the generic iTunes image of a musical note.  If I see 
Album Artwork, it better be because I purchased the track from iTunes, Amazon, Beatport, etc.
But with this new discovery (
new for me) of iTunes . . . . . 
on its own . . . . . . adding 
Album Artwork to tracks that I imported from my own CDs . . . . . . I am not happy.  In my mind, I expect to see 
Album Artwork only for tracks I purchased.
Today, I discovered its not just U2 albums.  Its with many other albums, too.  So 
now . . . . . . some of my imported tracks have 
Album Artwork and some don't.  iTunes thinks it is providing me a benefit, but its not a benefit for 
me.  I will now delete all the 
Album Artwork that iTunes added because I prefer the simplicity and the consistency of my long established way of knowing which tracks were purchased.  We all have our quirks and this is one of mine.  I just hope iTunes doesn't add the 
Album Artwork again . . . . . . at some point in the future.