The only thing that has consistently frustrated me with Android on Nexus devices (Can't speak for non-Nexus devices) is the "safety" feature when plugging anything into the headphone slot.
Seemingly randomly it will cut volume to 50% to protect hearing and you can't turn up the volume until you agree to a notification warning you about the potential dangers of high-volume listening.
I use this in my car. I need the volume max -1 click. Plugging in my phone and then wondering where the music is is infuriating. I don't want to have to pull over out of traffic just to unlock my phone so I can agree to a notification and then turn up the volume again. This wouldn't be a problem if it only asked me once, but it tends to "forget" at random times, usually when I'm in a rush and don't want to fuck with my phone.