That's not true at all. Copyright infringement is a strict liability offense with no inquiry in to the state of the mind of the infringer from a liability perspective. The state of mind of the infringer is only relevant to the issue of willful infringement.
It's just "infringement" and "willful infringement" there is no "less-than-willful infringement". Willful infringement is punitive with increased damages and increased burden to show - it's in the freakin' statute.