[throwaway219450]

The “tired mechanic” is apocryphal at best. ASD was intended to be clear to non-native speakers. Here’s an example from another page:

THE SYNTHETIC LUBRICATING OIL USED IN THIS ENGINE CONTAINS ADDITIVES WHICH, IF ALLOWED TO COME INTO CONTACT WITH THE SKIN FOR PROLONGED PERIODS, CAN BE TOXIC THROUGH ABSORPTION.

In STE this sentence appears as below:

DO NOT GET THE ENGINE OIL ON YOUR SKIN. THE OIL IS POISONOUS. IT CAN GO THROUGH YOUR SKIN AND INTO YOUR BODY.

Consider if you translated those phrases into a foreign language you’re basically familiar with. You can be awake as you want and mis-interpret the first one.