I'll bite. Why are absentee ballots the biggest problem?
By far the biggest vector for voter fraud.
The biggest problem is the electoral college.
and what problem does the electoral college cause?
The problem it was meant to fix is still disenfranchisement. The electoral representatives "are pledged and expected, but not required, to vote for the candidates they represent." Add in that states with small populations still get at least 3 votes and you get a situation where people say the electoral college "prevents the tyranny of the majority".
What problem does it solve nowadays? Why can't we elect our president directly?