I have no objection to cameras being placed in areas of concern as deterrents but in a lot of cases, they're not. There are two near me that are on stretches of road that I know for a fact, have had very few crashes and those that have happened, are the result of poor observation and discipline at give-ways on the junctions - not excessive speed.
Yup. It's fashionable and profitable to blame everything on speed. Excessive speed for a given situation does amount to careless (or even dangerous) driving, but there are so many other factors that are as or more dangerous.
Arbitrary speed limits bug the life out of me to be honest. They don't take into account the many variables that can change from day to day or even minute to minute. Often, the speed limit seems to be set for what would be safe on a rainy day in heavy traffic... and then enforced 24/7 even in good weather. I suspect that, more often than not, the people who assign new speed limits don't even survey the roads whose limits they change.
When it comes to motorway driving, relative speeds and stopping distances are a lot more important than absolute speeds. 90mph on an empty motorway is inherently safer than 50mph in a line of cars that are all tailgating each other. Similarly, passing an 80mph car at 90mph is safer than passing a 40mph car at 70.
As for safety cameras: They're often placed in response to a single but particularly serious accident. The examples that always spring to mind are the first ones that were installed in Liverpool. The cameras were placed in response to a speeding drink-driver who mounted the pavement and killed several people at a bus stop. The camera probably wouldn't have prevented this even if it had been there at the time, and had the driver sped past it, he'd have ended up with 3 points and a fine rather than the ban that he deserved.
But there was public outcry and something
had to be done. The cameras were simply a political move to appease the public.