1) Nice job, using anecdotes. Good on you.
2) Common sense has nothing to do with morality, or ethics (maybe slightly with ethics). What is usually thought of as common sense is only common in people with the same intellectual, social, and moral backgrounds. Telling someone who disagrees with a moral stand that they have 'no common sense' is useless, and morally wrong in itself, since it just shows you have no empathy.
3) Going with the above, morality changes with experience. Aside from simple mental maturity that increases with age, your experiences with other people and different experiences impacts what you feel if you are placed in a similar situation. For example, I am a lot more accepting of euthanasia than I used to be. It is still illegal in my country, but having seen some of the people that want to be euthanized and their pain and suffering, it's not so clear-cut anymore. Similarly, I used to be a lot more financially right-wing than I currently am, because I have realized from experience that it is the government's duty to advocate for and offer protection to those who do not have the means or the ability to help themselves.