> If you have trouble understanding this point, look at another country besides the US when thinking about it.
More than a little patronising, and also: really??
It wasn't a dig at the US, rather the opposite. Looking at say North Korea, or Nazi Germany, or any place where slavery was legal...might make it easier to see laws that were divorced from what is good/bad.
Many people have trouble thinking about the category of evil laws. It's not what they learned in junior high school! It's helpful to inspire thinking about categories that asymptotically approach the categories that are difficult to conceptualize directly.