I guess you are right and it's true that laws can be different. It's just that I prefer to not be limited by any laws. If some moral issue arises I prefer to think of what kind of answer my character would choose based on his personality, instead of what kind society he lives or lived in.
Usually I play either chaotic good or chaotic neutral.
grin I've played all the alignments, but I tend to default to neutral good or chaotic neutral, it seems, especially if I can't find an "edge" to play with like the aforementioned barbarian-paladin
In one of the campaigns, I play a character that is me transported to DnD world. In it I chose the chaotic neutral alignment.