WH - this just shows that nobody is perfect, which is more or less what I have always said.
People aren't getting any more clever, the PPL training certainly isn't getting any better, so CAS busts will continue.
Even so-called "professional pilots" get it wrong loads of times. Flying in UK Class G one hears a lot of absolutely appalling radio from pilots who I doubt know what they are doing. Flying airways one hears a lot of very bad radio from pilots who presumably fly the same route very often and get sloppy on the readbacks, often to the point where they are frankly unintelligible, so it is no suprise that mistakes are made.
To a large degree one could say this is the job which ATC are paid to do, and they are well paid too. One wishes there was a solution, but every time I suggest my favourite one, I get jumped on
