Tom69:I can see your point of view,but this will open a whole new can of worms and would affect all forms of transport especially public transport.Are we wanting obese people to pay extra for bus and train transport? I very much doubt it.
Why not? Charge them double perhaps some of them will walk as they obvioulsy need the excercise
And please don't start the its an illness whine, if it really is an illness we all know the cure excercise and dieting.