I think there are some flaws in the way you are describing the difference between western moral philosophy/ethics and Buddhist ethics.

First, the notion that there would be no objectivity in Buddhism to which one could compare the soundness or moral value of one's actions is just inaccurate. There are objectively wrong things to do: eating meat for example. The larger idea of an objective framework in which the individual finds him or herself confronted with the discrepancy between desires and expectations is universal, as I see it. It is the problem of individual and society, my wants versus my duties.

I think what needs to be separated for a good comparison between western and eastern ethical system is religion from the culture. *edit That is, we should separate religion from culture when thinking about comparing cross-cultural ethics: so we can compare American ethics to Indian ethics, but we should compare Christian ethics to Buddhist ethics. When studying the religion in particular, that is, just studying Buddhist ethics, we can never really separate the religion from the culture, since it is the surrounding culture that informs the ethical system of the religion./end edit First, we can call into question the division between west and east altogether, but let's just take it for the sake of conversation that there is such a distinction.

Western ethics has been associated with Judeo-Christian values, monotheism in particular, a set of legalistic codes and doctrines that one measures one's worth against how well they live up to these expectations.

Eastern ethics has been associated with a more diffuse, pantheistic, polytheistic, open-ended kind of "ethos" wherein the individual finds self-interpretation in the community and the local deities/practices/rites to which they ascribe.

Both of these descriptions are rather orientalist, and misleading, because they do not attend to the ways in which western religions have developed over time, they presuppose a fixed idea of "Judeo-Christianity" that is predominately Protestantized. The eastern description gives in to fantasies of the east wherein things are exotic, fluid, cyclical, "mystical," and so on. Both of these are caricatures that serve to re-intrench our understanding of ourselves and the other.

The more I think about it, the more it may be difficult or impossible to actually compare Western and Buddhist moralities because it seems like an apples and oranges situation. But I mostly came here to say that Buddhism does offer objectivity in ethics, the idea of "objectivity" can be called into question. Also that Buddhism does rely on mythology, of course, the Buddha was enlightened, and his story is of course the foundational myth that gives birth to the "religion."