Can’t grasp people can behave however they want

I listened to the first coaching call. I refuse to believe that people can really act however they want. Like another student’s question here, I can’t help but think of all the intentional terrible things people do to animals (and other people as well). How can it possibly be ok that people do really awful things that inflict horrible physical and emotional pain, etc. on other beings? The same goes for less extreme, but still uncalled-for ‘mean,’ treatment towards others. Shouldn’t there be certain golden rules (for lack of a better expression) for how people should(n’t) act towards others, just like there are laws against crimes because certain behavior is harmful/unethical/etc.? There really has to be times that people do in fact do ‘bad’ things that shouldn’t be tolerated. I’m really struggling with this idea. I get that when I think about the bad things people do (which I do often worry about especially in regards to animals), it makes me feel bad, but that doesn’t mean I should or anyone else should accept certain things that people do. Also, can’t angry or other negative feelings be justified when bad things happen? I mean, how could there possibly be a positive thought, and hence feeling, associated with cruelty, injustices, etc.?