Because I'm not always trying to scan something, like, if you're in the Starbucks app ordering something and you accidentally click the card screen and you're blasted in the face. I hate that shit, I'll turn my own screen brightness up thank you
Just instal an other brightness app (I still use Lux Dash) and don't use the android thing. I specifically add apps with QC codes as exemptions so it auto turns my brightness up. If you don't add those they should do them
So rooting is just allowing access to the root folders of your device and your kernel, rooting your phone doesn't do anything to prevent forced brightness changes
What about Lux - it's now discontinued but on my xiaomi mi 5 with a faulty brightness sensor that always reports full sunshine (and android 7) is doing miracles with the rooted plugin