Well, it might run off some passengers, but technically, it would be fair.
Weight affects fuel usage. Fuel usage affects cost to fly. They weigh your bags and charge you if your bags are overweight for that reason.
In a sense, by NOT weighing passengers, some people fly cheaper per pound than others, with the "others" who weigh less subsidizing their extra
pounds in their ticket cost.
They used to average out the weight of passengers and assign a particular number;
query.nytimes.com...
Since 1995, most airlines have assumed a weight of 180 pounds for each adult passenger in summer and 185 pounds in winter; checked bags are
assumed to weigh 25 pounds each.
However this averaged figure is proving to be inadequate. Clearly in todays world there are many, many people who exceed the 180lb average weight,
and since 60% of us are overweight here in the US, those anorexics that do travel are unlikely to balance the books.
There are safety reasons, as well, for wanting to know how much weight the plane is carrying;
query.nytimes.com...
Saying that overloading may have contributed to a fatal plane crash this month in North Carolina, federal aviation officials announced today that
thousands of passengers flying on small planes over the next month will have to tell ticket agents how much they weigh, or step on a scale, to check
whether existing estimates of average passenger weight are accurate.
Would it be inconvenient or embarrassing to be weighed like cattle at the check in? Sure, I suppose so. Would it be worth it to ensure that the
plane didnt crash? I think it would.
I doubt the airlines would pass the "cost savings" of tiny little passengers back to them, however, so it is likely to be a very lopsided
arrangement for ensuring that the fuel costs are covered. It would be nice if you got to add the amount of weight you "saved" by being under the
average to your total baggage allowance.