Leg room (or is it legroom) is a case in point. I can personally vouch for the space on a United Airlines Airbus 319 in economy. There is, for all intents and purposes (or a friend used to say, intensive purposes), none.
United touts the extra legroom in their business class seats, but it appears that they gained that space by squeezing the legroom in economy. The planes are no bigger. Maybe they took out a row of seats. Maybe.
Under any circumstances, it is really tight in there. (See attached photo.) It is worse when the seat in the next row is reclined.
That tiny space there? That's what is called leg-room. I pity taller people.