Neck restraints can be very effective in controlling aggressive behavior. The problem with them is that they require a lot of training and repetition in order to apply them properly. Unfortunately the majority of departments do not spend the time and repetition in training in order to assure that their personnel are proficient in how they are applied.
What you refer to as a "blood choke" is known as a vascular neck restraint. The principal behind this is to establish venous compression which results in congestion of the blood flow in the head and neck. Unconsciousness can occur in as little as five seconds. This is not a complete restriction of blood flow therefore life sustaining blood is still supplied to the brain, just not enough for consciousness. A vascular neck restraint is relatively safe for the subject, as long as it is applied correctly. We would consider this to be a "non-lethal" form of physical control.
When this technique is taught we would instruct the officer to trap one arm or shoulder of the suspect above their (suspect's) head before they compress the SIDE of the suspect's neck with their (officer's) forearm. The other side of the suspect's neck is compressed by the suspect's own shoulder (the arm "trapped" above the suspects head). Where this can go very wrong is when the officer fails to trap the arm and the officer's forearm shifts from the side of the suspect's neck to the front of the neck (over the top of the trachea). What started out as a vascular neck restraint (non-lethal) just turned into a respiratory neck restraint(deadly force)during the officer's struggle with the suspect.
Like you said, if you crush the Larynx or trachea, this is most likely a fatal injury. The upper section of the trachea, around the larynx, is easily damaged, similar to that of a Ping-Pong ball. Once it is crushed it is not going to flex back once the force or pressure is relieved.
I have been a use of force instructor for over 15 years now. My department does not permit neck restraints to be used for controlling aggressive behavior for the reasons I listed above. We simply don't have the time available to train our officers to the point that we are confident that they will apply the neck restraint properly. An exception to this would be as a last resort or when deadly force is justified.