The differential in the rear or front axle of the motor vehicle is necessary to enable wheels of one axle to rotate at different speeds. One of the wheels goes through the small radius and the other to the large.
That's why they're doing it at different speeds. It's the differential. If the wheels of the front axle or the rear axle were running at an equal speed, there would be slip, increased rubber wear and fuel consumption. This could also lead to oversteer or understeer.
Differential lock is used not only in off-road but also in sports
Differential lock is applied to both single or four-wheel-drive vehicles. The rear axle locking is necessary to increase the visibility of the rear axle and to improve driveability.
Sometimes, the differential lock of a single leading axis is used as a cheaper alternative to the full drive. Applies back and front differential locking and auto-port locking. The rear is in the drifting, and the front is in drag racing and the ring races.