I find myself wondering why someone from one of the lowest castes does not simply claim to not be that when they are halfway across the world from the society that has a tradition of maintaining this?

I can assume there’s a bunch of subtle class signaling that people do reflexively (speech patterns, dress preferences, whatever, I mean I live in a city with like five different distinct dialects that immediately tell a local what social stratum someone is from), as well as maybe an element of defiant “fuck you I am proud to be someone from the lowest caste who can run rings around your Useless Aristocrat caste ass”. Possibly some distinctive physical features due to centuries of it being forbidden to marry across caste lines?

I apologize if any of these questions are offensive, I know fuck-all about this. I also know it ain’t your job to explain all of this to my white American ass, a quick link to a good Caste 101 For Stupid Americans would be fine :)