I think one reason they make it work is that they have achieved better economies of scale in long haul operations simply because they HAVE to.
For example, how many +3000 mile trips does BA fly versus those that are 1500 miles or less? A very cursory glance at their interactive route map seems to indicate that many of their trips do go beyond the 1500 mile range(across Europe) with many to every other continent as well. The US airlines, by contrast, seem to have the exact opposite kind of model which naturally drives up the costs.