Besides propaganda, I don’t know why exactly. Maybe it’s a mixture of the detective mystery story plus that “might makes right” vibe as the detective usually doesn’t “play by the rules” and he’s a badass and Americans love that shit? Maybe the fantasy of having people with power also be moral and work for the greater good is just too appealing? A huge chunk of the world watches telenovelas the way that Western folk watch these shows, I think it says something about both groups, really.