The British police have done a few trials this year, where a plain-clothes officer rides a bicycle with a camera, and drivers overtaking with less than a 1.5m gap are stopped by another officer ahead [1].

What really bothers me is "over a 90 minute period in Bournemouth ... issued seven tickets to motorists for using a mobile phone at the wheel, one driver had their vehicle seized for no insurance or licence and another received a fixed penalty notice for not having a valid MOT certificate."

When the level of lawbreaking is that high, and irrelevant to the cycling bit, it shouldn't be a 90-minute initiative done with great publicity once a year.

[1] https://www.dorset.police.uk/news-information/article/3222 -- just one example, there are at least 10 results in Google with very similar press releases.