If the light turns red and you go through the intersection 0.1 seconds later, you're not going to cause an accident
If you go through at the halfway point of the red cycle, you've got an excellent chance of causing an accident
I'd think that, if the cameras were a little forgiving, people wouldn't slam on their brakes at the last minute.
No. I think there needs to be an easy line in the sand. If you enter the intersection on red you should get a fine.
If you are going to allow a half second or one second leeway on entering the red -- then it makes more sense to me to leave the hard line on the red, and just make the yellow 0.5 or 1 second longer.
I've given it a fair bit of thought actually, and I think the following is the best way to run the system:
100% of the revenue generated from any criminal penalty or fine should also be redistributed back to the residents in the form of a direct payment.
This ensures the city doesn't view the cameras (and any other crime) as revenue; and no part of the government becomes dependent on that revenue.
Then the city will make rational (and correct) decisions where and how to install and configure cameras, and when to decommission or rotate them elsewhere, based purely on safety objectives.
It does mean taxes have to go up a bit to cover the overall revenue loss; since enforcement is purely a cost centre now. But it balance out with the rebate. And having it go through the rebate and tax cycle means the costs/benefit of running the program is exposed directly to voters; and the city has no incentive or benefit from running a program unless it's actually working to improve safety, etc.