Airside Passes?
Some anomalies exist. Not all pilots have an airside pass, nor are they required to hold one. Some work from small airfields where no system for issue or checking them exists.
I last time I travelled to the USA the immigration officer ("We are the face of America" - oh dear, not a good start...) became very suspicious of me. I hold a USA business visa and have entered the country many times before, all stamped up and legal.
Having asked me what I did and why I was in the USA (annual helicopter simulator training), he said he wanted to see my airside pass. I told him I didn't have it with me as I was travelling only as a passenger and wasn't going airside during my visit. He said if I was a pilot I would have an airside pass. I told him in UK it wasn't mandatory to hold one and that I did have one but hadn't brought it along because a) I didn't think I would be expected to produce it and b) If I had brought it along I could be accused of attempting to gain airside entry when not entitled because I was not actually working as crew.
His body language told me he didn't like my answers at all! All sorts of other questions were asked; eventually he called a supervisor who thankfully sorted it out after about twenty minutes of me feeling like a criminal and holding up the queue.
The other anomaly is that it is perfectly possible to gain access to airfields where passes are mandatory without being required to show a pass.