For one thing, there is no solution to the Byzantine generals problem, this has been proven mathematically.
Cryptocurrencies sidestep it by saying "whoever is the luckiest (aka 'owns more GPUs') gets to decide the truth".
Traditional banks handle the problem by not having Byzantine generals: there is one and only one trusted authority who is compelled by law to keep clean and clear books. If a bank has a Byzantine problem that needs solving, they've already done something illegal.
For one thing, there is no solution to the Byzantine generals problem, this has been proven mathematically.
Cryptocurrencies sidestep it by saying "whoever is the luckiest (aka 'owns more GPUs') gets to decide the truth".
Traditional banks handle the problem by not having Byzantine generals: there is one and only one trusted authority who is compelled by law to keep clean and clear books. If a bank has a Byzantine problem that needs solving, they've already done something illegal.