Not entirely true. When you are 'caught' speeding somebody can and often does make an assessment of the situation and can decide not to charge you. If this were a public event played out on TV I am sure it would be enforced more strictly, but when it's more personal and intimate and flexibility is available, it's often overlooked. This discretion is available to and executed by the officer at the time.
Again the example doesn't help you at all. With regard to planning law, especially retrospective application of it the authority (this being the council) can also make an assessment of the situation, once that assessment and decision is made the defendant (in this case the Traveller community) have the right to appeal (sever times in fact) the decision and in this case they done so.
Once the final decision is made however, they, as you or I would equally be, are required to abide by that ruling. Why should they be allowed to flout the law simply because they are of a specific community?
They are as subject to the law as everyone else. If they do not agree with those laws then they need to engage with the society that makes those rules and like the rest of us contest them legally and democratically.
They are not above the law, and neither are you regardless of the nonsense ideology you may have.