Drop rate is about 1 per 50 kills. That is on average and given lots of events and means 49 ways to fail for every one way to succeed. Do *not* forget the variance. OP's pic can happen, given a long 'lucky' streak. I've also seen long streaks of none to few drops. That said, the Traveller's boxes do not drop from mobs under level 20 or so; at least in my experience.
"No sadder words of tongue or pen are the words: 'Might have been'." -- John Greenleaf Whittier
"Do or do not. There is no try." -- Yoda
On planet Earth, there is a try.
Indeed, in a world and life full of change, the only constant is human nature (A is A, after all :P).
We old vets need to keep in mind those who come after us.