Keeping tabs on weight is fine and It makes sense to use actual weights for w&b calculations.
However it IS discriminatory to charge people based on their weight.
Whilst one could argue that obesity is something that people could control themselves (besides some legitimate medical reasons), how does it work for tall people?
I did not choose to be tall, nor do I have any control over my height.
I am 95kg/210lbs. Sounds like a lot, but given my height, I am nowhere near being obese. In fact, my height vs weight ratio is spot on.
So why should I pay more than say a short, obese person perhaps weighing 80kg.
Whilst the headline gives some good press coverage, I can't see how this concept would work legally.