The uncancelled stamps don’t make sense either.
I spoke with a mailman the other day. I asked him how likely it would be for those fake bomb mailings to not be cancelled by the Post Office. He replied how overworked the clerks are and that each one is doing the work of 3. I then replied to him that there were multiple packages and all over the country. He just looked shocked as none of them being cancelled nationwide would've been highly unlikely.
Someone inside the postal system was complicit. How else could these be delivered on the same day all over the country if they were mailed in South Florida?