KLM went briefly to 23kg maximum bags for everyone -- including elites and business class passengers -- in order to protect the health of luggage workers but was forced to start allowing 32kg again for business class, due in part to all the confusion with DL passengers.
The latest changes on DL luggage allowance brought the JV the closest together it has been. Further future harmonization makes sense.
As to US domestic going to a max of 23kg to protect the health and safety of luggage handling employees, workers in the US don't have the same kind of institutional protections such as progressive employers, strong unions, tough regulators, etc. I would expect they will continue to be abused and exploited for many years to come.