Why is there no bodycam footage of any of these encounters?

Can anyone tell me why no bodycam footage of these encounters is released? That is a serious question. Logically one would think the police would protect themselves legally by releasing footage if it would exonerate them from blame? What is the legal reasoning why this footage has not been released? Bodycams would be a great tool in situations like this, all we need is for police to release the footage.