The sources of differences in ethics between people, companies, and nations.

Since you have tagged your question with health, I will
approach it from the medical ethics angle.

Cultural factors
have a strong influence on people's views of the value of life and the meaning of death.
In cultures where reincarnation is a common belief, death is not viewed as an outcome to
be avoided at all costs, whereas cultures that believe that each individual lives only
once may make much greater efforts to avoid or put off death. These two opposing
approaches affect the availability of critical care, life support, and resuscitation.
They may also affect when and how vigorously an individual seeks treatment for various
maladies.

Another factor is the cultural view of human
equality, or lack of it. In some societies certain classes of people are viewed as being
of less value than members of other groups. In a situation like this, those lower class
members - be it women, people of a lower caste, people of a minority religion, or
prisoners - may not bee seen as entitled to the same standards of
care.

For corporations, the sole objective is to make
money. A company needs to prioritize its activities in order to do this. If individuals
and their doctors are willing to pay for a drug or service, then companies will be able
to provide it profitably, and will endeavor to do so. Whether a company acts ethically
is to some extent in the eye of the beholder, as is evidenced by the debate in the US
over animal testing. Testing medical products on animals was commonly accepted for
decades, but public sentiment has changed, and companies are now being pressured to find
alternatives to animal testing; doing so may be the difference between being profitable
and going out of business.