Many of our arbitrary morals, even religiously influenced ones, are based on tribal culture and human biology. For example, chastising monogamous cheaters is o

Many of our arbitrary morals, even religiously influenced ones, are based on tribal culture and human biology. For example, chastising monogamous cheaters is one way to reduce jealousy and oxytocin-induced stress in a community. Following your example, anti-abortionists may see themselves as championing undefended members of society. Even in lieu of a privacy-free utopia where we fully analyze our motivations, I think we'll still have biological and tribal inclinations influencing our societal morals. (Unless this hypothetical utopia is so far in the future we've biologically evolved.)