Is it normal for people not to say or do anything?

It happened in a public transport. A train, you see.
The day was over and I was heading home, I was a relatively new contact-lens wearer and my eyes were feeling a little pained, because of that I decided to close my eyes for a bit.

The last thing I saw before resting my eyes was that a number of teen/late-teen -aged boys (I'd estimate around 8-9 of them)getting on the train. My ears were active, I could hear them talking really loudly and just generally being obnoxious. They started yelling 'BOO'or whatever equivalent to rouse me from my 'slumber', as if to jolt me awake just for kicks. I had no f*cks to give. I just got my ears pierced and my eyes were hurting, and I just couldn't wait to get back home, take off my contacts and play my video games.

And once did they grab my arm and pulled. Granted, it wasn't as if they were tearing my limb off but it was a tug. Nevertheless, I didn't think they'd actually touch me. I had to open my eyes to look at the boys in their eyes and yep, they'd look at me then look away and start sniggering. "tee-hee, tee-hee."

Now, I didn't give a crud about the noise and ruckus they were making. What happened during all that, was that a girl (who was sitting on the opposite row) called them out on it, she told them to leave me alone. They just mocked her and laughed at her. Everyone in the train (it was a bit full)just looked away and kept quiet. She didn't say anything after that, she just stared at them. They laughed even more.

The dipshits left after a few stations passed, taking away their noise. The train was in relatively 'peaceful'silence once again.

Nobody said anything on the train. I got looks from various people, as if awaiting I'd jump out from my seat, pull out a staff from sub-space and yell "In the name of the moon, I will punish you!"

Heck naw, I'm not a magical girl. I just kept quiet and tried staring daggers at them. (Despite my aching eyes), they DID cease the annoying attempts at waking me (I'm 'awake' now, so I guess their fun has ended, huh?)though they didn't stop with their loud laughter and chatter.

I couldn't give two shits why they picked on me. Was it my bleached hair (cuz i'm AZN)? Was it the fact that I was a female? Was it because I was 'sleeping'?
No, it was just out of convenience. They're just being pure assholes.

I doubt I'm much older than them. So I'm not going to go all 'kids these days-" I'm small sized and I look young for my age but what makes it okay for a bunch of people to pick on someone in a place full of people and when someone starts speaking out, nobody gives a crap?