Did you read the whole article? Down at the bottom was a statement from the election office.
It seems it was an act of mail theft, not voter fraud. And who assured you theft and fraud don't happen? What they told you was instances of fraud were usually minor and individual and not the sort of coordinated effort required to steal an election. Unless of course you're talking about conspiring to send fake electors to certify your fake results and you have a political party shameless enough to attempt it.