And why in heaven's name have they Koryfied Troia's uniform like that? Maybe Kory's works cause she has mysterious self-supporting Tamaran boobs but but sports bras are vital for human boobs for effective ass-kicking.
It's entirely possible that having bulletproof skin and dense, ultratough flesh might also make Donna's chest self-supporting as well.
Hell, I tend to presume that kind of thing about most superhumans, their bodies don't have the same realistic foibles as ours. It's basically a genre convention by this point.