There may be different reasons for that.
The AVRO has the AUTOSPLRS which deploy with speeds >33kts.
But we also use the Airbrake and Spoilers on our 146s during taxi to slow it down and keep the brakes cool. You see that especially in FRA on TXY S to RWY18.
And during lineup it sounds like the flightcontrolcheck.
With full handwheel deflection you have a pretty big rollspoiler deployed. And that thing is awsome big.