The crew can see the direct effect on their instruments - and in that case know what the cause is. When the SLF do it they don't know what is causing a potential error, problem, distortion or whatever.
That is the difference. When your radio is on the blink in many cases it is your only backup !!!
So we are in this case NOT talking about the drivers - but the rest of the souls inback. (I know its very much a case of 'do what I say' and don't 'do what I do' - but that is the way it crumbles cookiewise - as the transpudlians say).
