White have a few problems that have been identified. 1) the glass generates a low electrical current. The sharks know it's there, and are attracted to it. The less glass in the tank, the better. Most of the White sharks that have died, have died because they stopped eating. This indicates stress. When fish get stressed, they stop eating entirely. In predatory fish, their predatory instinct shuts off. The Monteray Bay Aquarium has managed to keep several alive for relatively long periods of time. In 2004, they caught and exhibited a juvenile female for 198 days. This was the first of six sharks that they between 2004-2011. None of them were larger than 2m, and only one was released because she wasn't eating. One shark did die a month after release, as it's tag stopped moving and popped off for collection, but no one knows why. Five of the six were released because they were growing aggressive and eating the other fish in the Open Sea Tank.
In 2016, an aquarium in Japan exhibited an 11ft (2m) male. It refused to eat and died. That is at the stage where they begin to transition from fish to marine mammals (10-14ft is the most likely size range of when a shark attacks humans. Actual adults (14-16st for males, and 16-8ft for females) are very good at recognize what is and is not a seal), and have played a part.
Adults would be impossible to keep, as they need fatty diets, and you can't just butcher a seal to feed a shark every week or so.