Of course, actual serious criminals who are actively committing serious crimes just use fake plates so they aren't affected, it only really helps catch people who commit crimes on the spur of the moment (while also obviously eroding every "normal" person's privacy)
They do put them specifically whereever those roads join major roads though. Meanwhile the crime stats in the UK make chilling reading, as the focus on replacing Police officers with cameras, replacing courts with... nothing has lead to many crimes skyrocketing, especially those that are not associated with driving a car.
https://www.ons.gov.uk/peoplepopulationandcommunity/crimeand...
A lot of people still habitually drink drive (not getting completely smashed, but a few pints at a country pub then drive home) and realistically as long as you don't crash you could do that for decades and probably get away with it.
There's almost no cameras and also almost no actual police
That is starting to change. Porch pirates incentivized a lot of people to invest in cameras and placing them in discrete locations. Some are getting clever making them look like owl nest boxes on poles, bird feeders and other benign boring objects.