I don't think the problem should be all that hard to identify. Executing a solution is the problem.
1. Is the airport doing it's part? Do bag belts work, are lanes of travel open, etc. If not, why isn't U holding them accountable? At some point, a non-functioning bag belt needs to cost the airport some $$$ to cover the airline's delivery costs and loss of goodwill.
2. Is the airline doing it's part? Proper equipment, staffing, etc. If not, they only have themselves to blame.
3. Are the employees doing their part? You can't say no to questions one and two, and then blame the employees. You can ask them to make do while corrections are being made, but then, you need to make the corrections in a timely manner. Once agents have the tools, hold them accountable.
4. Whose job is it to execute 1,2 and 3?