That's intentional. For the trial I sat on in January, the prosecutor had video evidence of the accused beating up one of his "employees". But she declined to press a charge for regular assault (with a one year sentence) as it was covered by one of the sex assault charges (which had a longer sentence). As it happens, we gave the guy a pass on the sex assault charges for lack of evidence, but the sex trafficking charge got him twenty years.
Conversely, prosecutors are charging police with capital crimes when they know they won't be found guilty. The textbook example is the Laquan McDonald execution, where Chicago prosecutor Anita Alvarez finally charged office Jason Van Dyke with first degree murder. That looks like a tough charge, but she knows he can get out of it on lack of premeditation or perceived risk to others. He might still be found guilty of a lesser charge, although I doubt it, but police shootings are controversial and the bigger charge has better optics in the press.