> One thing I'm seeing which irritates me is people are starting to call backing singers backup singers.

Rolling Stone magazine has been using the phrase "backup singer" for a genuinely long time.

https://www.rollingstone.com/music/music-news/dylan-gets-gos...

Fwiw, I used the same phrasing in my title as the product I bought on Amazon. Most of these are made (and packaged) in China: https://www.amazon.com/s?k=backup+camera A search for “reverse camera” only returns “backup camera”s