From what I understand match bullets do not have impact performance of your average hunting bullet. (Correct me if I am wrong since I have never personally shot an animal with a match bullet)
It's that expansion is not a design requirment, is why match bullets are "legal" in warfare (sniping).
It's not that they don't expand well, just simply that expansion is not a design requirment.
IIRC the core is actualy softer, IE pure lead vs a alloy, so they actualy tend to expand more (than a "hunting" bullet) at a given velocity or to expand as much at a lower velocity (2 ways of saying the same thing)
