One of the most devastating realities has been the fact that people for whom you truly care and for whom you do the most are often the ones who turn out to be the most ungrateful. They suffer deliberate amnesia (forgetfulness) and, in the process, even deny their indebtedness. Those for whom you would stake your prized privileges are often the ones who later undermine your integrity for the sake of fame or material gain. Such are they who have no conscience.
Conscience is that internal compass that directs us towards sound moral judgement. It measures our attitudes and conduct in relation to our ethical principles. Conscience manifests its judgements with the reward of peace of mind for those who do what they should, and with the penalty of guilt for those who don't. If we consider ourselves good, and don't have the decency to do what we should, then we are not really as good as we think we are.
Don't get it wrong, people do sometimes use "Thank you" and "I'm sorry" but merely as a hollow rule of custom. In one's absence they negate their thankfulness or regret in the company of others. Such "Thank you " and "Sorry" means absolutely nothing. We even teach our little kindergarten kids to say "Thank you" but too often it connotes only formalistic politeness without nurturing true feelings of gratitude. If we say "Thank you" without really feeling thankful or "Sorry" without experiencing real regret then these words merely serve as mindless rituals; just like a wrapped gift box without any gift inside.
The Messenger of Allah Muhammad [peace be upon him] said:"The Merciful One shows mercy to those who are themselves merciful (to others). So show mercy to whatever is on earth, then He who is in heaven will show mercy to you " ( Abu Dawud, Tirmidhi )