I don't think retests are the answer. Like an MOT where the owner goes home and puts the farty exhaust and wooden wheel back on, it's only good on the day. The most lethal driver can behave for one hour a year. Retesting will remove the nervous and those with health-related problems.
It works fine with pilots.
Also, Jimmy Saville and 'clunk-click' changed seatbelt wearing, how about adverts on driving behaviour?
British public information films did a great job in the 1970s, but that was when there were only three channels on TV, and often, because they were really well written, they were some of the most entertaining shows. Today, with hundreds of channels, they don't get anywhere near the same impact, and even if they could work with today's media, funding them in today's political environment would be next to impossible.
Here in the US, public information films have basically been relegated to the job of getting us to support wars and to be pro-American. They are little more than the propaganda wing of government. That's how the conservatives (and most of the liberals too) like it, and they won't countenance any funds spent on educating people - even if it would save lives. In today's anti-intellectual culture, education is seen as a Commie plot to indoctrinate people into Stalinism - I suspect it's a similar deal in the UK, since 'New Labour' effectively destroyed the progressive movement there.
Today, in order to have any sort of cultural impact, you have to get a film to go viral on the internet (like that Welsh one recently about texting while driving), and that's nowhere near as easy as having a captive audience, which was basically the case in the '70s.