I think one of the reasons things have changed for the better over the last 4 or 5 years at least is because the city government decided to put rubbish bins on every single corner instead of every second, and on both traffic lights on the same side of an intersection (two bins on each corner!). Now, to cross 9 de julio at Santa Fe, I pass 8 or 9 rubbish bins. It´s made a difference to those lazy people who won´t walk 5 steps out of their way to put something in the bin, but it´ll never make a difference for those who drop rubbish right in front of the bin anyway.