That's why some people can recite whole poems and other people can play songs from memory while singing them too. That's why you know just when to pause when you're singing to a song on the radio and the singer stops, and you know when the pitch changes, and what that particular beat is in the background that you follow.
There's more than enough details to be considered a violation of copyright.
Only few people remember thole poems and minority of people remember whole songs.
In any case, the number of fully copied items would almost always stay below one hundred (not hundred thousands).
And even those "copies" would not really be considered a copy by our contemporary judge (circa 2012). These are "backups" at best.
There's more than enough details to be considered a violation of copyright.