Dangerous Trend

Does the fact that police and law enforcement promote the use of CC-TV cameras in public places to deter criminal activity and for use in criminal investigations, yet balk at citizen use of recording devices to capture police activity in public spaces appear contradictory and self-serving? Or, do the police have a valid reason for citizens to refrain from recording such activity? Is it not in the best interest of the police to have citizens record their activity particularly when a citizen may bring a false accusation of excessive force or other charge?