I did some more looking and found that the survey points where they count modes of traffic are often bizarre. For instance a traffic count going into an industrial estate or a count on a B road off a trunk road that no sane cyclist would touch.
Had a quick look at Hertfordshire and they don’t have a single traffic count with cycles that goes beyond single digits in an hour. Which is bizarre as I can see more than that pass by in minutes when stopped at side of road on a ride.
So I’d say that their methods of assessing how many billion miles of cycling are done is flawed. They clearly assumed all roads are equal in some way to assess traffic. Whilst this may be true for motorised. It’s certainly not for cycles where a minor road they choose will see bugger all people cycling as it doesn’t form a useful part of any route.
You don't know the half of it. Other scams include detectors that ignore non-steel bikes, cycleways being excluded from counts of the road (only the carriageway counts) and automatic cycleway counters being decommissioned without adding an equivalent manual count point to the town's annual "inner cordon" count.
So serious injuries and fatalities are fairly accurately reported but ridership is drastically underreported, which farks casualty rates.
Even in places with better ridership data, it's reported months after casualties, so the press mainly reports the scary casualty numbers out of context and don't revise it after ridership is known, which is a mixed bag.