I do not see any problem with expecting people to pick up their own messes and clean up after themselves.
You're right, there is no problem with that. However lots of people don't see it your way and will leave their poops.......
If there wasn't a poop problem in the first place it's quite likely that the cans would never have been put there......
“I do not see any problem with expecting people to pick up their own messes and clean up after themselves.”
You would be amazed at the number of ‘special’ people who refuse to pick up their dog’s poop. Add to that the number of ‘immigrants’ who just leave their garbage in the park. When you confront them they get irate.