I don't disagree.
However, when they carry significant operating costs, it makes it more challenging to implement as it requires dedicated funding streams to implement and operate. And in that sense, it has to fight against other funding priorities which makes it tougher to do.
Speed Cameras have not been widely implemented in Ontario, especially outside of Toronto, largely because each camera costs hundreds of thousands of dollars a year to operate. Toronto has decided to spend this money so has proliferated them fairly extensively in the city. This is not the case as much in other municipalities where priorities differ.