We have a saying which says:
Every one sees the people in his own eye.
The explaination for this saying is:
If a person is miser then this person will think all people are the same and this is not true.
Now tell me if you are a lier or a cheater or hypocrite does this mean all the people are the same.
The person who thinks that all people are the same is either having a psycological problem or had many bad experiences.