Cartage pays for a job beyond playing
When an orchestra hires a harpist, getting the instrument to the venue can involve a separate task from getting the musician there. A harp is large and delicate, so moving it calls for suitable transport and careful handling. A cartage fee helps compensate the player for that added burden; it is not an extra payment for performing the music.
Why the fee makes sense
Without cartage, the practical costs of an orchestral engagement would fall unevenly on musicians whose instruments are unusually difficult to move. The harpist might have to arrange a vehicle and take responsibility for transporting valuable equipment, while a musician carrying a smaller instrument could travel normally. Paying cartage recognizes that difference and helps make hiring musicians with large instruments workable.
Double basses can qualify for the same reason: they are bulky enough to create special transport needs. The fee is therefore tied less to the instrument’s role in the music than to the logistics it brings with it. It turns an awkward, easily overlooked part of putting on a concert—moving the instruments—into a cost the orchestra can account for when planning the engagement.
