While I agree with the noise pollution, I dont think it’s worth the silence when there is a risk of pedestrians not noticing/hearing the vehicles. Especially in parking lots and busy roads, there is no sound when the vehicle is under 10km/hr.
The proposal is not a constant sound which would be annoying but to have a tone when the vehicle is moving slowly under 10-15km/hr. At higher speeds, the whining of the motor is enough to turn heads already.
I would also like to point to this thread, where such an indicator would help. Ownership Experience