But you don't know, do you?
Just like all the armchair phonies here who didn't know B-52s fly low, you're winging it to suit your prejudices.
B-52's can fly low, but I doubt they are doing that in Afghanistan. I am pretty sure they are doing what they did in Vietnam, dopping bombs in cells of 3, from about FL 300. They are much too big of a target to bomb from low level.