At the school where I instruct they recently made a rule that all passengers and students are weighed. I've refused to comply on the grounds that I only weigh 10 stone (140 lbs for those the other side of the pond). This means I can take anyone up to about 14 stone in the R22 with both tanks full, and up to around the max seat weight if I only fill the main tank - more than enough for an hour's lesson. This means I refuse to weigh tall skinny guys or little shrimps smaller than me. Believe it or not, I ended up in a huge argument about it.
Perhaps common sense needs to play a part here.