Why? Well, he really hates being told what to do. The presidency was supposed to make him immune from the law, especially from orders to return what he borrowed. That he had signed up to carry out a bunch of obligations and demands never crossed his mind.
The latest one, no doubt, has to do with the Uniformed and Overseas Citizens Absentee Voting Act:
The Uniformed and Overseas Citizens Absentee Voting Act (UOCAVA) was enacted by Congress in 1986. UOCAVA requires that the states and territories allow certain groups of citizens to register and vote absentee in elections for Federal offices. In addition, most states and territories have their own laws allowing citizens covered by UOCAVA to register and vote absentee in state and local elections as well.
And who’s in charge of enforcing that? The DoD.
The Secretary of Defense has administrative responsibilities for UOCAVA. Within the Department of Defense, the Secretary has assigned these responsibilities to the Federal Voting Assistance Program (FVAP). The FVAP actively monitors the voter registration and absentee voting opportunities provided to members of the Armed Forces, their family members, and U.S. citizens residing overseas. It works closely with the States to assure that citizens covered by UOCAVA have a full opportunity to participate in Federal elections.
No wonder he had a hissy fit at 2:30 in the morning.
Also:
"If a county is late in mailing absentee ballots to soldiers or U.S. citizens living overseas, what can the Department of Justice do?
Under Section 105 of UOCAVA, the Attorney General is authorized to bring civil actions to enforce UOCAVA requirements. When states have failed to make sure that ballots are sent to qualified UOCAVA protected voters in a timely manner, the Department of Justice has successfully obtained court orders and consent decrees. Many of these have required states to extend their deadlines for receiving these ballots and to count such ballots, even when they arrived after Election Day. In some cases, the states were required to make permanent changes to their laws or procedures to make sure the problems are not repeated in future elections. Through these cases brought to enforce the federal law, the Department has ensured that qualified servicemembers and overseas voters were able to cast their ballots, and know that they were counted."