Well, what a thread. Been away for a few days and can't possibly read it all.
There are just 3 ways I know of to make anybody perform better (whether it is flying, driving, sex, whatever)
1. Selection
There is none in the PPL training. Ability is not accessed (and varies widely). Anybody who can pay for the next lesson can come along, and most can get a PPL if they hang around for long enough.
2. Training
This one we could debate but ultimately the syllabus must be taught, and since "nobody" wants a longer (read: "more expensive") PPL course, you can't add extra stuff.
Much as many, myself included, like to have a dig at the ATPL hour builders that predominate in the PPL training scene, I don't blame them for the WW1 syllabus. Many may be poor flying instructors (in the sense that they are not good natural teachers) but most have, or are about to, pass the vast JAA ground school and are thus definitely not stupid, and are well capable of teaching procedural matters. And CAS busts are procedural failures, not flying failures.
The ontrack survey is largely a waste of time because it fails to identify the exact procedural factors that led to the errors.
3. Better equipment or procedures
What could one do? Dead reckoning is never going to improve (for a given level/type of pilot selection and training) no matter how long people rant on about it. GPS usage should be brought into the PPL as standard, but this can't be done without making GPS installation mandatory in training planes, which the flight training business will be dead against, which means it will never happen.
This thread has moved on to ATC procedures but I don't see where these come in. If a pilot isn't navigating then he will bust anyway. I suppose one could abolish CAS, then CAS busts would not happen, but this isn't exactly likely! I suppose that if CAS transits were readily granted (as in the USA, two-way comms are sufficient to enter Class D; the problem here is that the UK operates D as if it was B/C) then fewer people would be skirting around the edges of CAS, but this still isn't a solution to poor navigation because if you are allowed a CAS transit, the ATCO expects you to fully know what you are doing and not fly some zigzag track.
The UK has very little CAS. If people are busting it comprehensively (rather than going half a mile in, on a track parallel to the boundary) then something is going very badly wrong.