Pace - I agree. Having read through the cases for example I can see very little excuse flying an aircraft when you know it to have been grounded. The act its deliberate and a willful flagrant of the law.
Where a "professional" makes a mistake, it is more difficult. Did the standard of airmanship fall below that which should be reasonably expected? Where the consequences to have risked harm to others? What actions did the pilot take after the event?
I think these are some of the questions that the CAA should consider before prosecuting.
Many professional bodies "deal" with the discipline of their own members in the first instance unless a third parties insists on the matter being referred to the Court and they have the ability to censure and impose fines. In many cases this would seem a far better way for some of the cases to have been dealt with.