After a while, San Francisco residents get used to certain sounds. On Tuesdays, the emergency broadcast system issues a robotic test message. Sometimes the Caltrain’s horn can be heard echoing between buildings. And cans can always be heard as they’re collected and crushed in front of homes and apartments.
There is an underground economy of can collection in San Francisco. Residents sunning in the parks can be assured that their cans will be collected soon, and it won’t be by city workers. And those who collect cans know the days that each street will be putting their blue bins out for collection the next day.