Well... Even with the Moore tornado, if I'm not mistaken, there were only a few spot instances of EF5 damage (as is the case with any EF5 event; no tornado produces big, wide swaths of EF5 damage). Therefore, most of the imagery showing wide areas of devastation was actually showing EF3-4 damage. (Someone correct me if I'm wrong.)
For me, a good rule-of-thumb difference between EF4 and EF5 is that with standard wood-frame homes, EF4 leaves piles of rubble, whereas EF5 actually leaves the site swept clean. Like, it won't even be clear what was at that location before the event occurred. So, a casual glance of the Tuscaloosa images I've seen says EF4 to me.
But, again, I am no expert and don't pretend to be. There are people in this thread who actually do these surveys, and I'm sure they'll shed much brighter light on this topic.