There is a quality check in the process to ensure correct registrations are taken:
1. minimum 3 volunteers by the roadside during a deployment.
2. our group has one volunteer to solely captures the registration, and this is corroborated by their colleagues.
3. we check our records against public databases to ensure match between registration and noted vehicle details, and filter out any obvious goofs before submitting to the police.
4. we have to capture registration, vehicle colour, make and model.
5. we have to transpose our records from the roadside into a spreadsheet to ensure we interpret our own handwriting correctly, and submit the roadside records to the police in case any queries are received from the drivers.
To be honest, given that the drivers eyesight is obviously so bad that they didn't see all the speed limit signs I'd be more worried about the visual capabilities of the drivers than the CSW volunteers.
Yes, we do catch a lot of locals - which is great, since it's also the locals that tell us they want something done about the speeding, so ultimately they put pressure on each other to conform. However, we also record lots of commuters who pass through the parish on their way to work, and delivery drivers, school buses, 8 wheeler tipper wagons doing 50+ etc. I've heard people say "I always keep to the speed limit in my village, but don't elsewhere"