I questioned DVSA about this, basically as my wife runs a Polo with an AE211 engine, a 1.2TSI 110PS, their answer is, various checks and balances need to be made concerning every report incident, if the classification and/or in consultation with the car manufacturer, or their official importer, they find that they have been convinced that there is no safety issue, then "no flags" are set and no action is required.
In this specific case, VW Group importers have advised DVSA that the owner/driver will always be aware when a failure has occurred, and should just pull of the road and stop - DVSA will hand out this to everyone that reports this issue, but if numbers increase, they might reach that tipping point and change their minds.
It is true that the driver will eventually get a warning light, probably for low fuel pressure, but I fail to see that that changes anything, this is thought/said to be caused purely by an assemble line equipment failure leaving these 4 high pressure fuel rail securing bolts too loose/not tightened to the correct torque, and that causes high pressure petrol to spray over the front on the engine, being drawn back to the exhaust+turbo area in the slipstream - not nice.
For me, this is an issue that should be classed as a safety issue and must lead to a recall for all VW Group cars fitted with these engine types built over the production period covered by this assembly
problem, and no ifs or buts.
At a guess, a possible 25% of all cars having this failure will get repaired within the VW Group workshop umbrella - the other 75% at the most convenient workshop using VW Group parts, all recovery/breakdown assurance provider will take the car to the nearest fixer, and most people just want their cars back running as they only have a car to use it. So VW Group workshops and even VW Group Indies will see very few of these failures, a better measure of how many have failed might be to quantify the number of bolts and /or injector seal sold for these engines - but VW Group will not be interested in doing that "just out of interest".
Edit:- it is only the 4 cylinder engines, ie 1.2TSI and 1.4TSI that were being built over the estimated period that are effected.