What about singing, or whistling, or humming? What if it's not music, but a TED talk blasted out at full volume? Will there be additional fines for singing out of key? And how loud is the limit? If one uses open-back headphones prone to sound bleed, does that count?
Who will be enforcing this? If a case goes to court, what counts as evidence other than eye...well, ear witnesses?
What if it's just kids? Are they expected to pay the fine? What if they're too poor to pay the fine, will they be arrested for the debt?
What I'm saying is I hate people blasting music on the bus as much as anyone, but allowing it to become law that's supposed to be somehow enforced is both stupid and a flagrant justification to abuse authority.