https://en.wikipedia.org/wiki/Backup_camera

it is also used very regularly elsewhere, like government sites: https://www.nhtsa.gov/vehicle-safety/driver-assistance-techn...

or legal advice sites: https://thelegalguide.org/are-backup-cameras-required-all-ca...

or news sites: https://abcnews.com/US/cars-us-now-required-backup-cameras/s... https://www.reuters.com/article/business/consumer-groups-sue...

or automotive magazines: https://www.autoweek.com/news/a1892066/feds-backup-cameras-a... https://www.caranddriver.com/car-accessories/g44411856/best-...

it's safe to say that "backup camera" is perfectly acceptable.

A reversing camera is handy for people on one side pond when they take their estate down to the tip to chuck out a load of rubbish.

Backup cameras are useful for people on the other side of the pond when they take their station wagon to the dump to get rid of some trash.

I'm British and to me backup means having a reserve or spare ready to use. You have a battery backup on your servers to step in when there is a mains problem, a photographer will have a backup camera, you backup you files regularly etc.

We would call this a reversing camera, for when you reverse your car using the Reverse gear. You can back into a parking space, or even just back up a little bit into a better spot.

One thing I'm seeing which irritates me is people are starting to call backing singers backup singers. They are not a backup the the lead singer, that would be an understudy, they are supporting like the backing on picture.