I worked for a company that manufactured these machines including electro-mechanical systems as well as the software that used for configuration and generating reports.

The way it works is, these machines would either read the printed barcode or take a picture of the label and run through OCR engine, use the zip+4 and sort them to a bin based on some configuration. Then these bins would go on a truck to their destination.

The machines are not doing the routing. So your fears are unfounded.