I don't think 'rational' is the right word. Responding to incentives, in this case a monetary disincentive, is rationality. The tenants are either lazy, care little about the appearance, don't put much thought to the issue, don't know they're doing something wrong, or don't care because there is no disincentive to anonymous trash-leaving (especially because other tenants are doing it).

So maybe a better title would be "don't expect people to think just the same as you."