When DeJoy, the recent USPS admin was hired by the former US President, he is allegely a logistics guy and started to make changes, which also tended to delay the workings of transporting the mail for distribution. His apparent desire was to make things more efficient by limiting some activities, closing facilities that were under-performing, etc., by observation and various news reports.
From my observations, there are BETTER ways to do things in a customer-focused business operation. To seek to be a better operation than what has been there in prior times (decades), by observation. Many people want to blame the unions, but I also would put blame on management for not getting the unions on-board, as partners, to ensure things work as well as they can, even if it might take some extra efforts by all involved to make it work as good as others tend to make it work, even better when possible. To me, the rewards of this approach can be very good.
By my observations, unions exist for a reason. On the same hand, THEY should help ensure their paid membership is the best it can be, worthy of the higher wages they typically are paid. A "different dance" than both sides' management is used to dancing, too. Everybody has to TALK to each other in a professional and civil manner for best results, as BOTH sides seek the best way to do things to result in the best outcomes in the end. Rather than one side seeing the other side as an "enemy" (which in some cases, they can be).
FWIW,
CBODY67