I completely swung my bag into a seated passenger's head today! I think I might have done it a couple times before I realized what I did!!! Once I realized, I felt so bad! I turned around and caught the horrid and anguished facial expression of the woman who is the victim of my careless arm motions.
She looked pissed. But I was already in the middle of my sincere apologies, "Oh my god, I'm so sorry! Are you OK? Sorry about that!" I didn't quite smile but I probably had an innocent "oops! my bad" expression on my face. The woman suddenly turned from mean and angry, to nice and laughing!
She responded, "It's ok, no worries." and smiled back at me! What a 180!
Well, I was relieved. I did feel very bad. I remember being in the very same situation with people's computer bags or gym bags knocking on my head! I was pissed off too!! But they never said sorry.
Maybe some politeness and common courtesy on BART could make it more pleasant?