This wasn’t a robbery. This 91-year-old man apparently was attacked because he’s Asian. Or maybe the attacker is just mad at the world. Moments later, he assaulted two other people.
In a similar attack in San Francisco a few days earlier, an 84-year-old Thai man was killed. That assailant was caught. The motive in that case apparently was that the victim looked at him while he was vandalizing a car.
Read about these incidents here, here, and here.
https://twitter.com/i/status/1357410040462733312