The truth is the prosecution bring a lot of sexual cases to trial which they fully expect to lose. They feel they have no choice. The alternative is a lot of angry complainants denied their day in court and a lot of probably guilty accused who would never face the accusation. Twenty or thirty years ago it was thought better not to bother with the expense of such trials. Now the policy is to run them even if they lose. The fame of the accused is barely relevant to the decision, but fame does probably mean that the prosecutors would face greater criticism for a decision not to prosecute. The decision is put in the hands of a jury. A jury does not and can not give reasons. The jurors are anonymous. Newspapers simply can not whip up anger directed at the jurors. The jury is the pressure release valve in the system. You have to feel sorry for the string of jurors to whom responsibility for delivering the inevitable acquittals is buck passed.