Standard weights are always tricky. I understand that an airbus FBW aircraft can tell its pilots a pretty good aproximation of its weight once airborne. On our airbus fleet on a full aircraft apparently usually the aircraft think it weighs around 2 to 2.5ts more than calculated vial loadsheet figures. And we nearly never use charter weights anymore, instead split figures for business passengers of 88kgs, 70kgs, 35kgs and 0kgs for males, females, kids and infants. Holiday charter would be 83 and 69. However, flight crews are considered at 85kgs and cabin crews at 75kgs, both values are quite often wrong as well...
Airlines would weigh passengers if they could, and charge them for any extra weight. Alas political correctness stands against it.