"Consent", when used as an excuse, fulfillf the role of all types if excuses in blocking the inference from what appears to be state that a person with good desires would not have created to the conclusion that the agent who created it deserves condemnation. Condemnation is a tool used tp promote good desires - desires that people generally have many and strong readons to promote.
A person is caught driving his brother's new and expensive car. When he is accosted with the fact, "That's not your car," he answers, "My brother said I could take it."
One might be troubled as to whether the claim is true or false (particularly if one knows the driver's brother and the brother's dislike for letting other people drive his car). However, the claim itself fits the excuse in the second category described above. No wrong was done because the owner of the car gave his consent. The state of affairs is not one that a person with good desires would have reason to avoid – though it may look that way at first glance.
In another case, Person A behind the wheel of a car aims for Person B. Person B tries to get out of the way, running left then right. He trips, and the car runs over him. This creates a state that a person with good desires would have wanted to avoid.
However, we learn that the driver and the person he ran over were members of a stunt crew working on a movie.
We could call this an accident. The "accident" excuse may protect against condemnation for the state in which the victim was run over – at least in this case. However, it does not excuse the state of aiming the car at the victim – that was no accident. That was done intentionally. Furthermore, it is something that a person with good desires – with an aversion to causing harm that people generally have reason to promote through condemnation - would not do.
When a person uses the excuse of consent, they admit, "this appears to be a state that a person with good desires would have tried not to realize. However, I checked with the most knowledgable and least corruptible authorities on the matter, and they assure me that this is not the case."
Where each person seeks the objective satisfaction of their own desires, they have reason to support an institution that will allow those desires to be objectively satisfied under conditions where those intimately affected agree that this is likely.
So, the movie company hires the stunt crew who plan out a a stunt so that it objectively satisfies the most and strongest desires (given the beliefs of the agents involved). The director is provided with the effect she wants at the price she affords, created in a way that protects the health of the members of the stunt crew and compensates them for their expertise and their risk.
Normally, aiming a car at somebody (let alone paying one person to aim a car at another) is not an act that a person with good desires would perform. However, "We checked with everybody intimately involved. The most knowledgable and least corruptible agents all agree, we can objectively satisfy the most and strongest desires this way. QUIET ON THE SET! PLACES, EVERYBODY!"