Through no fault of the evidence...some people are just dumb that way...
OK, but a set of data only has meaning once it's interpreted. It doesn't exist in a vacuum. It is inserted, for example, into a legal procedure, that of a trial. If the people doing the interpretation are doing it subjectively...
An analogy: a virus is often inert, even at times subsisting in crystal form, if it is not interacting with a living cell. Once it does interact with it, then it becomes in a sense alive... starts reproducing genetic material or altering the host cell. If the virus infects certain cells - like the HIV infecting lymphocytes - it might do a lot of damage, while if it infects other cells, it may stay dormant, with the host becoming a carrier, but not sick. Same inert virus, becomes active when it interacts, two different cells, two different results.
The evidence on its own has no meaning... it's just an inert piece of data. When you make it interact with prosecutors, juries, defense lawyers, judges... then the matter of how convincing it is will come into play, and it will acquire meaning. That meaning resides in the heads of the people considering the evidence, like a jury. They will call it sufficient to create certainty of guilt, or insufficient, therefore leaving space for reasonable doubt, because people will have different (and subjective) thresholds for what they consider convincing. Not to forget, defense lawyers and prosecutors will deal with the same objective evidence, and do their best to subjectively make it different, to fit their purposes, usually in a very opposite way.
And the thing is, the exact same set of evidence might be interpreted differently by a different set of jurors, thus jury selection (when lawyers try to pick jurors likely to be most favorable to their side).
Say there is a mistrial aborting one trial, the case is tried again, so the same evidence is presented to two sets of jurors.
Even though you're calling it objective, it might be subjectively interpreted quite differently by those two sets of jurors; one for example inclined to consider the defender guilty, another one rather esteeming the defender not guilty.
Same evidence, leading to two different conclusions... once it interacts with the different (and subjective) psychological make-up of those people.