TPE-HKG is the busiest international air route in the world, carrying well over 5 million passengers per annum. As such, it clearly lends itself to both high frequencies and high capacity aircraft.



(Note that all other routes in the Top 15 are domestic services. Note also that the numbers are the O&D traffic on these routes - onwards/connecting passengers have been stripped out)

In general, large/widebody aircraft are inefficient for shorthaul services. The planes age faster/work harder [far more take off/landing cycles per day and per distance travelled means they are being used inefficiently and expensively]. Additionally, customers and airlines prefer a high frequency on short hops, so airlines rarely "merge" several of their frequent short-haul services into a single flight operated by a larger aircraft, as it actually reduces the airline's attractiveness on that route. Which would you prefer - 2 daily A380 services from CDG to LHR, or an hourly shuttle on an A319? (The former, of course, if the timing suits, but for people who value the flexibility to travel at any particular time of day, or to be able to have flexibility in their plans, or who simply cannot or do not want to wait around all day for the next flight, they will take the next available shorthaul service)

That said, I always choose the widebodies when flying on Qantas domestics, wherever possible!