Cheap Flights from Buffalo to Atlanta from $98

I realize this may not be PC but how can you justify charging the same price for a 5' 120lb person as you would a 5' 300 lb person? Our height we have no control over, our weight we DO! Nothing more uncomfortable than being next to an obese slob that is half on my seat. Start charging by the lb and watch the weight start falling off, just saying its getting out of control. One other option is to have specific flights for excessively large people( not Height) where there are fewer bigger seats and the cost is higher. Its getting old and something must be done!