While not every car comes with a backup camera, it's likely they will in the near future. The National Highway Traffic Safety Administration is considering making it a law.
Carmakers have used ingenious ways to incorporate these systems into cars. Some have video screens in the rear view mirror, cameras and sensors are hidden in the trunk or bumpers, and other cameras offer a computer generated bird's eye view of the vehicle.
The systems work superbly to keep a driver from backing into a small child, or over something left in the driveway--bike, scooter, skateboard. And for aging baby boomers with arthritic necks, it is a God-send.
As the cost of these systems continue to decrease, it only makes sense to see every car get a backup camera, as it's something every person does when driving every day.