"Isn't this the way it's supposed to be?"
No. The threshold is 'beyond a reasonable doubt', NOT beyond any doubt. This muslim female was an accessory to the murder of almost 50 U.S. Citizens.
I believe that the definition of "reasonable doubt" used in military courts is the clearest description of that phrase:
A "reasonable doubt" is not a fanciful or ingenious doubt or conjecture, but an honest, conscientious doubt suggested by the material evidence or lack of it in the case. It is an honest misgiving generated by insufficiency of proof of guilt. "Proof beyond a reasonable doubt" means proof to an evidentiary certainty, although not necessarily to an absolute or mathematical certainty. The proof must be such as to exclude not every hypothosis or possibility of innocence, but every fair and rational hypothesis except that of guilt. The rule as to reasonable doubt extends to every element of the offense, although each particular fact advanced by the prosecution which does not amount to an element need not be established beyond a reasonable doubt. However, if on the whole evidence, you are satisfied beyond a reasonable doubt of the truth of each and every element, then you should find the accused guilty.
As an aside, the last time that I was called for jury duty, the judge asked all of the prospective jurors if anyone could define "reasonable doubt". Having been a military and civil service court reporter for 40 years and having memorized the definition used in military courts (as a result of having heard and typed it thousands of times), I alone raised my hand. She gave me a quizzical half-smile and asked me to explain. Well, I repeated .. verbatim .. the description of reasonable doubt with which I was familiar. When I was finished, she shook her head and informed me that this wasn't a military court and there was NO definition for reasonable doubt, that everyone's definition was .. and should .. be different. I just shrugged and said, "Whatever you say, Your Honor ...".
Needless to say, I was not seated as a juror ...