OC,Let me give you a little insight into an mot station.These are generalised but you'll get the idea.
To be a tester you have to be a fully qualified technician at least over 21yrs old,and pass the course(can't remember but 2 days?)then you go back to work,shortly after a regional vosa rep comes out to watch you do a dummy test at your garage.He signs you off and you're good to go.
Now to your question in your last post,garages are traffic light graded by vosa,green=good,they only come out to see you once every 3yrs usually half day,watch one of you do a test,check all paperwork and training is good,Amber=good,but you've done something to be on their radar,been caught out by a mystery shopper,missed bits,poor paperwork etc...they will usually call in once a year or so,Red=poor,you've been up to no good,example,local guy did 27 tests a day for 6mths,7days a week!they set up surveillance,went to jail for 6mths,guess what,back trading I believe.(basically he was logging on 10mins not even doing a test)they'll be round frequently.
As for your other question,we have to read all special notices and make our own decisions based on how we interpret it,this is why so many grey areas,Nobody has ever come from vosa and explained anything about changes EVER.
They're only normal people,but it's a bit like the tax man turning up unannounced and demanding to see all your paperwork,you do wet yourself

they have the power to shut you down there and then,even something like missing play in a ball joint.So if you think mot testers are being a bit harsh on you,they may think you're a mystery shopper?
Hope this gives you a little insight into our world.