From where I stand as general remodeling contractor in Los Angeles, the reasons for peeling paint can vary widely. Painting over dirty walls, excess moisture, improper prep, and using latex paint on top of oil paint can all affect the paint's adhesion and cause it to eventually begin flaking off.

For you case, it looks like paint was applied over a oil paints, besides the walls being dirty with no proper preparation. Unfortunately, doing another coating on top of it will just no help. You'll just need to have the paint scraped off and do a fresh one. Simply, you'll need to remove the peeling areas and start over with fresh coats of primer and paint.

Make sure all the layers (even the previously existing one) are scraped off. Also make sure that you choose the right paint that will fit you home's atmosphere in terms of moisturization.

No. The walls were not properly prepped for the new paint.

I see it happening a lot with more modern paints like BM Aura and SW Emerald, even on properly primed and prepped walls. The paint seems to stick down better after a couple years. It happens less often with cheap paint, at least from purely casual and anecdotal observation. I'm guessing it has to do with what they've had to do to make lower VOC formulations.

Looks like latex over oil. A painter should have known better. Probably improper prep too. Obviously, no primer. It needs to come off, and then cleaned really good, and primed with a sealing bonding type primer, and then two coats (proper wait time, between coats) of a good quality paint.

Since the back of the peeled portion looks like it is white, apparently the primer isn't doing its job. Perhaps the wrong primer?

How long ago was the primed & painted?