The US Congress is on the verge of ordering the FAA to rule against airlines desire to reduce the size and pitch (pitch is the distance from a point on one seat to the same point of the seat in the next row) of airline seats. That desire is governed by greed and standing room has actually been mentioned. The FAA has so far refrained from such ruling. Hopefully airline passengers will have some more space – or at least not less space – where to suffer long flights, which are not very comfortable in tourist class in the first place. Pitch used to be around 35 inches and are now sometimes 30 inches or less.
In the US the question of space is more of an issue than almost anywhere else in the world, since the size of the passengers has an opposite trend. Obese passengers are a problem airlines have to deal with, and they do in in different ways, constantly wary of possible discrimination law suits. Passengers might be offended from being forced to pay for an extra seat to not being allowed seats at over-wing exits (where there is more legroom) where they would effectively plug the window exit and rendering it out of action.
There is a slight, or actually rather acute, unfairness in the area of weight. Since you sometimes have to pay for overweight baggage you might look with mixed feelings att . your fellow passenger twice your size at the next counter, paying exactly the same amount per kilo – for the baggage. The only really fair fare would be per total amount of kilos, since airlines are in the freight business. It will probably not ever happen, but putting everyone on a scale and charge a kilo price might in America give airlines resources to even install a few really large seats. Utopia comes in many shapes.