Well not actually by the government, more like by public bodies. There's a creeping adoption of systems that weren't designed for advertising being used to continuously broadcast messages.
You can't catch a train without being told the platform might be slippery because it's raining - so don't run, not to leave cases unattended (or the security services might blow them up,) not to leave children unattended (presumably the security services won't blow them up) and that "closed circuit television cameras are in operation at this station."
The tannoy system was put in to let people know that the 6.30 from Waterloo is late again and they might as well walk home, but it's being used to broadcast constant messages aimed at behaviour modification.
The same is true of Motorway dot matrix screens, that are supposed to be there to warn you of problems ahead. They're not needed most of the time though, so why not harangue drivers about drinking, drugs and the dangers of towing a trailer?
Outdoor owners can't advertise next to motorways because the ads would be a distraction - although that doesn't stop enterprising farmers parking branded trailers in their fields - so how are these messages from the Highways Agency acceptable?
We need guidance right across public service bodies that broadcast systems put in place to communicate essential information are for just that. Not a free, unregulated, advertising channel with which to shout at the UK population.