The salient point being that having a "secret" ballot has not stopped it from happening either. My employer can easily verify if they choose if I have donated

The salient point being that having a "secret" ballot has not stopped it from happening either. My employer can easily verify if they choose if I have donated to the "correct" candidate already and rampant job discrimination seems not to occur in a significant amount. So, one has to balance the risk of someone acting illegally in either case to discriminate against/coerce versus the increase in voter participation that would naturally occur in having online voting that was verifiable. I think it's an easy case to make, but perhaps I'm overlooking something.