... I notice that an awful lot of people who use the cycling is so safe line when it comes to helmets don't seem to apply it to discussions about speeding motorists, badly designed cyclepaths or close overtakes. Why bother to get exited by these things if overall it doesn't matter? Cycling is safe: Drive at whatever speed you like why doncha?
Cycling is safe. Roads and cyclepaths are safe. Bad driving (which includes driving too fast) isn't.
That is why the fiercest opponents of helmets oppose helmets so fiercely, because once you start wearing protective clothing (or demanding segregated cycling facilities) you are accepting that the roads are dangerous and trying to protect yourself rather than looking for a better solution which would be the removal of bad drivers from the roads.
Cyclists make up less than 5% of road accident deaths but it could be argued that bad drivers cause nearly all of them.