Just curious, what stops Indians from faking a different caste? Wear the thread, smear the ash, get a name change, use sunblock if you'll be in the sun, and sud

Just curious, what stops Indians from faking a different caste? Wear the thread, smear the ash, get a name change, use sunblock if you'll be in the sun, and suddenly by choice you are a Brahmin? What am I missing?