The unreadable codes

The donation appeal asked people to put a collection code on each parcel. Some donors wrote a name instead. Several codes were blurred by rain during delivery. A few parcels contained items intended for two different collection points, although only one code appeared outside. The contact sheet listed telephone numbers without matching every number to a parcel. We could not open packages marked private, and the driver needed the sorted load before his next round. Setting aside uncertain parcels was slower but safer than guessing their destination.

Describe the difficulties of sorting the donated parcels. You may support your points with brief quotations.