I agree with your points except that reducing speeds by even an average of 1mph does appear to reduce both collisions and the severity of those accidents by abo

I agree with your points except that reducing speeds by even an average of 1mph does appear to reduce both collisions and the severity of those accidents by about 5%. https://www.edinburgh.gov.uk/downloads/file/32217/evaluation-of-the-20mph-speed-limit-roll-out-three-years-post-implementation https://www.edinburgh.gov.uk/downloads/file/32217/evaluation...