There is an interesting photographic essay here on the enforcement of road charging in Germany. This is the sort of thing from which your average journalist could benefit - but won't.
I didn't realise, for instance, that the enforcement agency can interrogate your OBU, via an infra-red link, using a hand-held monitor. In theory (and practice) therefore, police can carry out real time roadside checks on cars fitted with road charging equipment – without stopping the drivers – to find out where they have been. Unless the drivers are subsequently told, they would be totally unaware that their movements had been checked in this way.
The civil liberty implications of this are horrendous.