The message
from "Dave Plowman (News)" contains these words:

The saving on the collection and enforcement would be substantial but
the DVLA would still be required to keep track of cars and drivers so it
would make sense for the tax disc to metamorphose into a visible MOT
certificate.

Too open to fiddling. It is far too easy to buy an MOT without the car
being tested - so the same would apply if private garages carried out the
annual registration too.

It is easy enough to print one but that applies just as much to tax
discs. But would a MOT testing station operative really risk his and his
employers livelihood by registering a MOT certificate without carrying
out the test? It would only take one to come unstuck for the whole
business to collapse and with the computer link there is no way the
perp. could argue that someone had copied his details off a genuine
certificate.

Fake MOTs could presumably be of some use in obtaining a real tax disc
at the PO counter but so too would be a fake insurance certificate. But
if going down that route why bother. Automatic number plate recognition
is out there looking and the first thing plod seem to do after stopping
a motorist is a vehicle check which would immediately expose any
clerical forgeries.

--
Roger Chapman