Lomapaseo
Well, "chummy" can mean the local FAA guy him(her)self doesn't cross-reference all the weights on file: in the onboard W&B paperwork; in the airframe's FMS; in dispatch's paperwork; in the maintenance records; in the master file at HQ. Never assume that even "good guys" can't get a little lax, now and then, trusting the operator's processes because they are also "good guys/gals."
I'm not knocking either the FAA or SWA (for whom the fatal event was their first (onboard, aircraft failure) in 51 years) particularly - human mistakes can creep in anywhere. You catch 'em, you tighten ship.