[DanielK]

Well you learn something new every day. I had clicked on the notification settings, but as it took me to my phone's settings screen I didn't bother looking at the 'notification categories' option. I suspect that many other people are probably also unaware of that feature, and I've now changed it. I might check a few other apps on my phone to see if they also have a similar setting, which I'm guessing is utilising and Android OS feature.

Worthy to point out that many apps do infact integrate the Notification Categories into their app, so that you can set it within the app and it sets it in the OS.

Media apps seem to be the odd one out and don't do it.