Mitigating circumstances, normative ethics
The universalisability of norms does not mean that the western people all factually follow these norms. Even if everyone were to lie, the ethical statement “No one ought to lie” is a universal moral statement.
The existence of debates about abortion, war, etc. is indicative of the nature of normative rules. Because “one ought not to kill”, debates and doctrines about “justified war” come into being. It is important to note that these doctrines do not contradict the injunction not to kill but provide justifications for undertaking such an immoral action. (They provide, so to speak, the mitigating circumstances.)
Same about abortion. If you follow the debates, one side tries to argue that ‘abortion’ is not murder of a human being (e.g. the fetus is not yet a human person); the other urges against it because it is ‘murder’.