I would not trust the flight crew, as they can not see the actual situation or like in the Iberia case obviously choose to ignore it.
The voice of a true professional.
I have and always will investigate a passenger query even if it is just to put them at ease. However, if one is regulated and paid to do a job, in any industry, then some element of trust in their proven ability (when I say this I mean ongoing regulatory training and examinations.) should be expected.