Morality and Ethics. By their definition, they are subjective concepts, like beauty. No matter the logic, the philosophy, the fame of the author, any description is merely their opinion.
More important is the purpose of morality/ethics. When seen as the foundation of a society of people it had an altogether different meaning. In this instance, it is the code by which the group govern themselves. As such, it must be defined by the consensus of the group so as to really represent their point of view. This cannot be flexible. If the code is broken the society falls apart.
The current migration globally has brought this into the spotlight. Unless it is a condition of migration that the immigrants abide by the code, the society will break down.