And this directly violates my own personal experience. I've shared food with my bro and dad, both of whom have far more spice tolerance than I do. I'm able to handle spicy food well enough, but there comes a spice point where I'm having the "intense sweating, uncontrolled crying, sinuses gone haywire, face turning pure red" reaction you'd expect from a cartoon character, and they're both fine, looking perfectly normal as they enjoy the same thing that's giving me malaria symptoms. It is not just a mental "they enjoy the pain more" difference, their bodies are straight up not having the same physiological reaction that mine is.
This is a far more plausible explanation. "Sydney isn't any more resistant to spice than most white people are, biologically speaking, but her whole family is really into super-spicy food so she's been mentally associating it with good feels since forever, so Lapha is getting all the suffering without the history of personal experience making it enjoyable".