Due to the large wing span the spolier deflection is required to assist aileron control whilst at low speeds. Due to the larger wing span the spolier deflection is more apparent.
On the Boeing and Scarebus, it is often the case at lower speeds the spoliers assist aileron. I think, without going into my books, 10 degs of aileron inpuit on the B737 causes a spoiler deflection so got to be careful when putting into wind aileron during a xwind T/O not to deploy the spoiler cos can cause perf reduction.