Why aren't volume controls based on average power output or something?

Maybe this is just my phone (and laptop), but volume control is irritating when some tracks are configured so that I need to set the volume to 70-80% and some tracks are so "naturally loud" that the lowest setting (5% ish for my phone) is distractingly loud.

On some of my tracks (especially for the classical music ones), within the same track I need to change the volume from 20% to 80% depending on what part I am listening to if I want to hear everything without killing my ear drums.

I get that it would be difficult to do anything about this for streaming or live audio since the phone doesn't know in advance what the input will be, but for a pre-recorded mp3 file, couldn't my phone do some digital signal processing?

Do I just have terrible electronic items and is this an issue anyone else experiences? Ot is this problem just harder to solve than I am expecting?