I believe the goal was to stage a 'look at this half empty truck leaving the distribution center, why is Dejoy delaying the mail?' photo shoot. Trucks start rolling from P&DCs at 1am to make it to the stations in time, ideally the late truck would make the most dramatic photo opportunity since it'd be mostly empty since it brings back the equipment the clerks sorted out of at the station.
You must be a Postal worker!!
Maybe as a member of Congress, DWS assumes a MPC is not necessary. After all, in her habit of thinking, the most efficient way for a carrier to deliver mail would be to personally drive it to the places to which it is addressed.