In the UK (Where the op picture is) the police cannot collect the revenue from cameras and other fines. It all goes to the gov so the cops have zero financial incentive to install speed cameras.
The most viable alternative to traffic stops is a narrow chicane with solid bollards on either side, although oher traffic calming devices are available.
Traffic cameras exist to generate revenue, not to make the streets safer. Intersections with red light cameras almost always have shorter yellow lights, to increase revenue while making the intersection less safe.
No. Traffic cameras in your area are there to generate revenue.
The camera being covered here is not at an intersection so your offtopic comment about revenue is irrelevant. This is a camera on a stretch of road where drivers usually speed, the cameras are painted bright yellow to make them obvious and do a far better job of getting people to slow for hazardous corners than a sign ever did.
In California the duration of yellow is determined by a formula incorporating the roads speed limit. If yellow light duration is less than the formula would set, the traffic ticket is dismissed. I'm guessing most states have a similar law.
They do not exist solely to collect revenue, although they certainly do that as well. They have been proven time and again to reduce speeding and fatalities, as other commenters in this thread have pointed out.
As far as using traffic cameras to reduce police forces, I haven't been able to find that exactly, but there are plenty of examples of deploying traffic cameras to work around a shortage of officers which works out to the same thing.
For reasonable people yes, but those that go 30km/h over the speed limit every time don't care and will always drive as fast as possible in those sections. I once met a guy who claimed to know down to the exact last km/h how fast he could drive until the car lost control in every single curve of a quite curvy road segment. Is it save to drive like that? Absolutely fucking not. Does he car(e)? Also absolutely fucking not.