Originally Posted by Often1

The FAA investigation is a significant flight safety issue and has nothing to do with check-in.

All other major US carriers scan the tag on each bag as it is loaded onto the aircraft. This provides an accurate count of the bags loaded. That is multiplied by an average bag weight and that number (along with which baggage compartment has been loaded) is provided to the Captain and to dispatch and forms part of the W&B calculations.

WN does not bother with scanning and relies on a hand count by the rampers. Sometimes they screw up. When they do, the count is off and W&B may be affected. While it's not likely to cause significant risk, that is not a certainty and there is zero tolerance for this level of sloppiness in US commercial aviation. It's one of the reasons why flying is so safe.

The technology required is hardly sophisticated, but it is necessary. It has ancillary benefits if WN wants to bother, such as permitting passengers to track their bags on the app.

Bottom lime is that that this is a significant safety issue and has nothing to do with whether bags are weighed at check-in and what WN does or does not charge to check bags.