In my opinion a Govt (or singal centralised, not for profit organisation) sponsored and managed licencing scheme is the only way to go.
I know that the licencing issue has been chewed over several times in the past, but a recognised (by Joe Public) licencing scheme which had teeth to weed out the rogues and which provided a set of rules to operate by would encourage sceptical Joe to have his car repaired by you, the approved, licenced expert, over "Bodgeit and Scarper".
I agree that paper based assessment alone is not the way to ascertain if Fred is a capable technician or not, it must be a combined practical and theoretical assessment, but not just on raw technical ability alone. Our customers want quality assured, honest value for money service and repair completed by a professional to a professional standard. If not, they have some redress and the rogue trader could be penialised.
Never mind the flash sineage and the fancy mags; proper, consistent, regulated, licenced auto repair outfits have got to be the way to go.
I truly believe that this is one of the ways in which we could begin to earn a fair days pay (as a licenced operator), and it would promote the trades image and begin to encourage school leavers that a licenced motor trade job is a job worth working towards having.