Maybe speed is less of a factor in accidents becwuse people drive more slowly, due to speed cameras.Don't throw numbers around that make no sense, it ruins your argument entirely. Around 97000 people were killed or injured (that's shock through to arm hanging off) on the roads in 2017. Between 2012 - 2016 speed was a factor in only 11% of all accidents, it is only the primary contributory factor in between 5-7% of all accidents. Governments own figures.
We need a grown up common sense based discussion about the use of speed cameras and other types of enforcement, not arm flailing and wailing about the children, being hugely emotive doesn't help us target limited resources at the right things, as evidenced by the angst in this thread.
Certainly in the south east many motorways have become smart motorways with average speed cameras.