Remember that the verdict of "not guilty" is not the same as "innocent". We can't take away Ghomeshi's freedom, but we can send him to counselling, warn women, or other things that do not require judges and cops.
If you are familiar with hypothesis testing in statistics, it is the exact same idea. Your null hypothesis (innocent) is accepted by default unless you have overwhelming evidence (a very small p-value) that your hypothesis is not true. In that case, you reject the null hypothesis (and convict). But with a lukewarm evidence (not tiny p-value), you just "fail to reject". You never actively accept the null hypothesis.
This is why "not guilty" is not the same thing as "innocent". A court does not attempt to establish someone's innocence or not. A court is biased towards convicting only in the face of undeniable evidence. And that's why things such as whether the victims contacted Ghomeshi after the assault or not are "reasonable doubt" and thus he's acquited. Not because the court proved that the assault didn't happen, but because the court failed to obtain undeniable evidence that it did.