I was wondering if someone knows the answer. I send my films to a film lab to be developed, I got back the pics and checked the negative, around 6 photos were not developed. Most of them were clearly not fully good, like I accidentally opened the back and half of a photo got destroyed, or others are quite underexposed but they are still visible and clear to see on the negatives what's on them. I don't know much about developing so that's why I wanted to ask: Why were they not developed? Is it because these are harder to develop at all? Or the film lab made the decision in my place judging them as bad and undesired photos? 
"Bad" photos are still very useful to me as I like to experiment here and there and if I don't get the end result it's harder to say what I messed up. (I'm asking here and not the lab because I don't directly go to them, I send the film through someone else and only in about once a month.) Thanks in advance for any answers!