She wasn't arrested for jaywalking. She was arrested for failing to provide identification.
You have to know someone's identity to write them a ticket.
Again, the cops could have handled the situation better (been more understanding of the fact that she didn't initially hear them), but they were completely in the right in enforcing the law.
The city has been cracking down on both pedestrians and drivers (as well as bicyclists) as we've had several years in a row with record breaking numbers of pedestrian fatalities.
Cop has two choices when enforcing piddly laws and the suspect won't cooperate.
1. Ignore it, let the suspect get away. This is a moral decision that may make it unreasonable to justify enforcing the law at all.
2. Enforce the law by all means necessary, including chasing the suspect down, and making an arrest. This causes a big scene, and makes everyone cry foul.
Both are a lose lose situation :\