We don’t all see eye to eye. Perhaps the humane treatment of others doesn’t rank high in your priorities. That self-awareness is important.
A business is not a charity. The management approaches contained in the manual are designed to be effective. They will help the people you manage perform well over the long-term. This will make your job easier and make you more successful.
Even if you genuinely don’t care about others, it will be better for you if you manage like you do.