For me the following is quite a convincing perspective: Slavery has existed for most of human history. The inherent cruelty has only in recent times become som

For me the following is quite a convincing perspective: Slavery has existed for most of human history. The inherent cruelty has only in recent times become something understood widely as morally wrong and unacceptable. We have abolished slavery and while it exists in some forms and niche cases, the majority of mankind looks with disdain and hate at those still practicing it, and with shame at their ancestors for accepting and tolerating it. (Factory) farming/slaughter of animals has existed for most of human history. The inherent cruelty has only in recent times become something understood widely as morally wrong and unacceptable. We will abolish farming/slaughter of animals and while it will still exist in some forms and niche cases (eg pharmaceuticals?), the majority of mankind will look with disdain and hate at those still practicing it, and with shame at their ancestors for accepting and tolerating it.