Some products can be self certified (ie: the manufacturer ensures they are built to the relevent standard without submitting them for testing) - however it is all to easy to chuck a CE mark on a product without carrying out tests.
If the screwdrivers are as bad as you say, I'd take them to Trading Standards and get them to investigate how dangerous they may be - especially if someone is relying on the insulation.
If someone in the EU were to wrongly mark goods, they could face a prison sentance, but with all these cheap imports it's impossible to police the manufacturers.