I understand why app developers do it, and their motivations are often well-intended - like with making QR scanning more reliable as you mentioned.

It still makes me annoyed, because as far as I'm concerned things at the system level should be under my control, not handed to apps.

My complaint is ideological.

If anything I'm annoyed at Android (=Google) about it, because they could at least put it behind a permission and let the user decide whether to give apps the power, but no - apps can do it whether you consent or not.