"Shame isn't a strong enough emotion to stop us doing anything at all"

Hi.

In your opinion, within the context of the movie's storyline and/or in general, what do you think the above quote means? And is it to be taken literally and/or metaphorically?

Is it meant to be about rape in general? Or even other bad and violent deeds? Also, if this is true, can I also ask...

Would the main male rapist of the movie, and another male serial killer also, even FEEL shame, literally and de-facto, as in, feel it in the first place, and then STILL proceed to doing any of the deeds? Aren't they meant to be PSYCHOPATHS or SOCIOPATHS who feel no conscience OR shame in doing what they do, which means, since they CAN'T feel it, then it isn't just about "it" and how it isn't strong enough to stop them.

Also, if that isn't, then what is? Would CONSCIENCE or EMPATHY then be strong enough as emotions to restrain us from doing anything seriously wrong? What about the LAW? Or COURT OF PUBLIC OPINION, even if neither are perfect and are basically human inventions?

Of course none of it can ever excuse, and at times may not even "explain" either, any of the deeds as such, and they are to be seen as horrible and wrong no doubt.

But I wonder, what, if at all, would the above quote and phrase really mean? Thanks.