because people throw their trash on the street. so it's everywhere.

americans are not as clean as most europeans, asians, or canadians. we are big on throwing shit out the car window.

i bike/hike a lot. most of the trails where i live are loaded with trash. dog shit bags, snack wrappers, bottles and cans, and often camping equipment abandoned. people refuse to bring it back to their car.

and if you confront someone who throws shit on the street, they threaten to beat the shit out of you. they don't say 'oh my mistake, let me pick that up'.