The way I understand it, 'safety inspection' is supposed to make sure everything is in correct position before applying electrical power to the airplane.
Have a look at the procedure. You ensure that radar, flaps, gear, eng masters etc. and last but not least, wipers are in safe position. Only THEN you switch on batteries/Ext PWR/APU.
While leaving wipers accidentally on will probably not kill you, it's not good to have them running on a dry windshield and scratch it...