Earlier quoted context omitted.
The are police and other public sector unions. The point of unions is to protect labor interests. Unions can exist as long as labor does.
And those police unions are exactly why in many cases, an officer gets to see ALL evidence and video about a situation, with a required rep or lawyer, before making an official statement in many jurisdictions. Something you and I certainly don't get. In fact, they often try to trick suspects.
But that's not inherent to a union. Cities shouldn't cede these extraordinary powers to the union in the first place, and if they already have, they should take them back.