I am not from Canada, but my country for decades has been using speed cameras and I think I can give a perspective about them being “tax grab”.

The answer is, it depends on the situation, but in my country most of them are NOT tax grab. You can tell when they are when the cameras (or the police officer) and the speed limit is done in a way to trick people. One such case is when the speed limit is lowered (usually in highways) but there is limited signage and/or effort to inform the public about the change, so drivers that are used to the road ended going at the old speed without noticing. Another case is when there is an abrupt change of speed limit, some times over a corner or even without and change in the road that would make sense the limit change, or even if it is a limit change that makes sense but they put the camera right at the change when a lot of people have not yet have time to slow down.

So I feel like, if the speed cameras in a place are tax grab the solution is not to remove them but position them where they make sense.