Some cars have 2 gears as well. One for the acceleration and one for cruising efficiency and top speed. So my guess is to get it going easier and then have 2nd as the eco gear for the speed they cruise at.

I am unsure sorry, electric motors do still have efficiency curves so that could be it. But I think a retrofit to an existing driveline makes more sense.

Food for thought though, trucks are much much heavier loaded than cars. 100-150+ tonne vs like 1.5-4 tonnes for a car. Cars are trivial by comparison.

Perhaps the motor they have available doesn't have enough torque for it without gearing down.

> Perhaps the motor they have available doesn't have enough torque for it without gearing down.

This is true of cars too - the single-speed transmission in a Tesla is a 9:1 reduction gear, for example.