Precisely for the same reason such systems have been saving flightcrew's necks for the past 30-40 years .. they provide an independent gross check on
(a) loadsheet mistakes due to finger trouble
(b) loadsheet mistakes due to weighbridge defects .. very important for freighters where it is super easy to end up with a very, very large incorrectly reported can weight (OK, mass ..)
(c) physical loading errors .. the next time a can load is put in back to front, or the cans get mixed up ...won't be the first .. or last ...
I have experience on two systems in years gone by .. neither was terribly accurate but the error was reasonably consistent so the gross check need worked fine ... one just kept the zero error in mind when comparing apples with oranges ... saved my neck once or twice along the way.