Are speed cameras really effective? There are multiple studies that looked at this.
And the answer is yes, they are:
https://pmc.ncbi.nlm.nih.gov/articles/PMC1963295/
https://pmc.ncbi.nlm.nih.gov/articles/PMC3861844/
The car crashes that happen in Ontario cost society far more ressources (police, hospitals, nurses, medication, surgeries) that any of the money raised by speeding tickets.
Road narrowing is a great idea. It can be applied to local streets.
But the people who hate speed cameras are going to absolutely FREAK OUT if you suggest road narrowing as a potential solution.