I mean the answer is pretty obvious. We don't care about problems with online banking; we force banks to care - if something (anything) goes wrong, the bank is

I mean the answer is pretty obvious. We don't care about problems with online banking; we force banks to care - if something (anything) goes wrong, the bank is on the line for any losses, worst case scenario is, a bank collapses. With voting, whoever is the online voting provider (even if it's "the government" i.e. the bureaucrats and the party/parties currently in power), isn't really responsible... if some things go wrong, nothing happens... if too many things go wrong, the whole system collapses.