Here in Europe the budget airlines charge extra for carry-on luggage that won't fit under the seat in front of you and even more for hold luggage. The whole business is based around a 30 minute turn-around from arriving at the gate to pushing back. #Ryanair is the notorious leader of this sector. Of course, there's no Business nor First, but they seem to cope well with a very large proportion of passengers with one standard size wheelie bag.