I think it usually doesn’t come up because Singapore is a very complicated country, perhaps the most “outlier” country on the planet. Most people in the US (even well-educated ones) don’t know nearly enough about the social, cultural, and historical dynamics to speak on it intelligently, let alone compare and contrast it to a country like the United States.

Might as well talk about drug policy in South Sudan to be honest.

Edit: I will say I do have one Singaporean expat friend who finds capital punishment for drug possession vile, and cites it as one of the reasons she no longer lives there. Along with the crushing wealth disparity between the servant class and the working class. Not that it adds much to the conversation except personal flavor.