However. I think I would not be flying again due to the public humiliation of having my weight analyzed every time I fly
That is utterly bonkers. No-one's weight is going to be announced and even if the check in desk person sees your weight, if you are noticeably under or overweight, they can tell that by looking at you, so I really don't understand what difference them knowing that you weigh 6, 8, 16 or 18 stone or whatever makes in the slightest, especially when they see hundreds of people a day and will probably never see any of them again.
Josepheen It's not an allowance, it's an assumption based on statistics used to calculate the weight of goods (passengers, luggage, fuel and other items) carried on the plane.
There is a statistically significant difference in the average male and female weights, so by noting that they have X men and Y women, each multiplied by an average weight, they have a rough indication of the weight of people on the plane.
What a lot of people seem to be forgetting is that we're talking about an average, which by definition means that some people are below and some people are above and for these purposes there are no medals to be gained for being above or below that number.