Because elections have strict secrecy requirements that bank transactions don't. Once you cast your ballot, it can longer be associated with you. So if someon

Because elections have strict secrecy requirements that bank transactions don't. Once you cast your ballot, it can longer be associated with you. So if someone hacks the election equipment to alter the ballots, there is no way for you to find out that your ballot was altered or to reverse the alteration. In contrast, fraudulent bank transactions are routinely discovered and reversed.