England and Wales, Scotland and Northern Ireland all have comparable strategies that seek to sustain and maintain a population of healthy honeybees - in NI it is known as the Strategy for the Sustainability of the Honeybee. There are working groups focusing on particular aspects of the strategy such as the competence/education of beekeepers, communication, disease etc. The minutes of the regional groups are available online - I think I found them via the FERA website and DARDNI website. Beebase might also have some links. The Scottish Executive sit as interested observers on the working group for England and Wales. From those minutes you can identify who is on the committees and thus you have an avenue to advance your views and hopefully have them given due consideration within the working and implementation groups. If the bee inspectors are to be given teeth and beekeepers are to receive greater information from FERA, NBU and associations, these working groups are going to have to push for the funding to support these things.
I'll make it a little easier for you: I sit on one of the England/Wales Fera Healthy Bees Plan working groups that you describe.
The issue of sale of nucs has been discussed at length, particularly the aspects of poor quality and of poor record keeping. The latter obviously exacerbates the former when trouble arises - as you say inspectors have to do a lot of legwork to locate nucs sold by beekeepers who are reluctant to disclose or who never recorded the information about who they sold to.
The best information a beginner can be given is to ask around to find a reputable supplier - and this applies to far more than just beekeeping. You point out in your example that the local grapevine knows who the iffy beekeeper is and where he operates (and more beyond!) - most beekeeping associations are just the same. This forum is a case in point: beginners taking the time to ask "where should I buy a nuc from" this summer would have seen a number of threads advising extreme caution with a small number of unreliable sellers.
There are a number of issues with coming down hard on a small number of rogues. The first is that there needs to be proof of a knowledge that the colonies were diseased, then that this was concealed. To use a "three strikes and you're out" approach would require changes to legislation, and would risk forcing some fairly shadowy characters further from view. It also needs to be able to deal differently with those who are incompetent or unobservant from those who are deceitful.
Ability to recognise disease is an education issue. Look though at the discussions on education here; many want to learn, but some don't feel the current education routes work, and some simply don't want to be educated or contradicted and will actively resist being told. I often give the advice of "go and spend time with your bee inspector" yet - and this is not a dig at Ron - it seems to fall on deaf ears. There's nothing like seeing foul brood in the field and watching how it is diagnosed - from signs on the comb to LFD results or making up microscope slides - to get your own awareness and recognition up to speed. I do it at least once a year to "keep my eye in" and it's why I had the confidence to stop a demonstration last year and say "This colony has EFB" based on a handful of duff larvae, despite it being a high-profile apiary with foul brood likely to cause some embarrassment.
Equally important is that as soon as bee inspectors are seen as coming in and shutting down beekeepers' operations, other beekeepers will become a lot more wary of them. Imagine the uproar on here, for instance, particularly when anyone who is "anti" rushes to put the boot in. Their current reasonably free access and the perception that they are welcome "health advisors" and not "disease policemen" would be shattered, with much greater consequences for the general health and wellbeing of our bees.
All this has to be balanced to ensure that any response is productive, reasoned, and proportionate.