Not a fair comparison. Bank databases have been running since the 70s on code that has barely changed in that time. They've been battle tested for decades, so it's unlikely a new exploit is going to be easy to find.
On the other hand, if you wanted to run an election on a centralized database, think about what that means. All the votes need to go to 1 server somewhere, which will tell us all who won the election. A server that is run by an IT team who will have root access and could be phished, or bribed, or threatened. A server that only gets a real-world test once every few years.
Users have no idea if their vote is in the database, if it's correct, if it got counted in the final vote or not.
Don't get me wrong, I don't trust the current crop of DLT tech more than the pen and paper method, but at least it's more transparent than a centralized system