Another thing that needs to be factored in is the seating density of charter airlines. For example, compare a charter A330 with up to around 350 pax, compared to a scheduled carrier that may have 250-300 pax across a variety of classes. The available overhead stowage is pretty much the same (give or take a few wardrobes, galleys, etc) but you have up to 100 more cabin bags that need to be squeezed in.