All the more reason to be aware of your environment. You're either aware or you're not.
Just because you're enjoying that freshly brewed pour-over with earbuds in listening to your favorite tunes or diving into your favorite book sitting in a comfy cafe doesn't mean you should turn off your radar. Personal protection is more than self-defense training or combatives. It's about the overall safety for yourself, your family and those around you. Develop an informed awareness, make it a standard practice, plan, and stay aware of your environment and situation.
(Location: West Chester, PA)
And if you think it's a one-off scenario, click here for a slew of other examples.