Roger, your description from watching "Cops" is all-to-often correct. That was my original thesis on this thread. Most officers receive minimal training in overcoming resistance and then don't practice it often enough to be really competent. That is often why you see several dealing with a single suspect. With well-trained officers you may also see several restraining a single individual, but doing so in a highly competent manner. As for the "stop resisting" orders, you may be right in some cases, and in others you are unable to see and feel the suspect's actions to know if there is any active resistance to be overcome. I'm sure that there are some officers who are intentionally using excessive force - it happens and I've fired a few over the years as well as testifying against them in civil cases. Most do their best to follow the law and behave properly, but the problem is lack of training even with the finest officers. There are a host of reasons for the lack of training, lack of interest; budget limitations; competing training priorities; Fair Labor Standards Act, and others. As you are surely aware, martial arts skills are perishable and must be practiced frequently and consistently.
I am not acting as a police apologist here - on the contrary. I want all of our officers to be well-trained, well-supervised, and well-disciplined and I continue to try and make that happen. I probably scream at the TV louder than most when watching "Cops" and police procedurals.
Often, I see both the officers and the "offender" struggling, it does indeed look like the offender is resisting, but from training in DR and more recently in Aikido, I have a sympathetic viewpoint at times, where I KNOW that the officers are trying to apply a control in a way that causes pain - encouraging the very movement they see as resistance. If that's true - the solution is in the training as you have said - each officer should have lots of experience in both sides of the different pins.
That's how it seems to me in any case...