Protecting the ecosystem... kind of it's own point. Protecting agriculture would be another point.
There's 100 reasons for customs, but we'll go with this one. Are you cool with dogs that obviously have rabies randomly coming into your house? What do you do with moldy fruit/bread?
Customs isn't about keeping the country clean. Also, I dont see how this would affect the agriculture of the home. Maybe it is because I dont pay farm subsidies in my home.
