I know what you mean but it wasn't funny when I was recording my kid at his first birthday party and got interrupted by a robocall just seconds before he cut the cake. From that day, I've learned to put the phone on DND mode before recording anything memorable.
What I don’t understand is why Apple isn’t fixing this.
It’s simple - it’s broken UI, Android has done it, people want it, it doesn’t help in any way, so why keep it? I mean why? Hell, if you really want to keep it, give an option to disable it.
Add this to the list of reasons why advertising is a cancer on society. Without robocalls and telemarketers, calls wouldn't be an annoyance.
(Though I agree that they should be relegated to the level of notifications now. Smartphones are computers. Imagine if Skype call would lock you out of whatever you're doing on your desktop.)