If some punter arrives on the tarmac and demands to check out my plane, is it permissible to establish the legitimacy of their identity and authority before allowing them to violate my presumption of innocence?
Most certainly. Anyone who is claiming to represent authority over you has to be able to back that claim up - with ID or other worthy credentials.
I've done it to a plain-clothes policemen in an unmarked car, when he pulled me up and started acting a little "bolshie".
He only had some red and blue flashing lights on the dashboard and he was wearing a suit. After he started coming on a little "bolshie", I requested - and I was entitled to request - ID verifying his claim as a Police Officer.
He didn't object and immediately produced photographic Police ID - and I would expect any Govt inspector to do the same, if requested - no matter what field of industry he operated in.
There was a recent case here of an idiot selling his cars who posed as a Qantas FO, without any qualifications. He went to the trouble of acquiring a uniform and forged papers to impress potential buyers.
The two vehicles he sold still had money owing on them. He was duly nicked - for impersonation as well as fraud. He wouldn't have fooled me, of course - everyone knows FO's are nearly all broke.
'Fake pilot' admits car sale fraud - The West Australian