Speed cameras are often a revenue tool rather than a safety improvement. Sudden significant changes in the limit, or placing a speed camera at the bottom of a hill where a driver typically may temporarily exceed the speed limit as the adjust to the grade can be used to generate revenue and a speed camera automates that process.
A cop patrolling or sitting by the side of a road provides a visual clue that slows down drivers; you could argue that speed camera warnings improve safety by slowing drivers own.
The problem with red light cameras is the timing of the yellow. Adjust the timing so as more drivers get caught is entrapment and leads to more rear end collisions as drivers slam on breaks. In addition, some jurisdictions made them an administrative fee too to do an end around about your ability to contest them in court, no doubt to avoid having to deal with an influx of cases. So yea, I consider them entrapment and a number of jurisdictions banned them for good reason.
No, that's a cop doing their job and exercising judgement on what is unsafe.
Having it installed does not equate to using an app. While I agree many users will use an installed app by default there's certainly a significant percentage of users, based on my experience, that use Waze or Google maps. I'm not so sure Apple Maps are an iPhone user's overwhelming choice.