Protecting the ecosystem... kind of it's own point. Protecting agriculture would be another point.
If you have kids, do you let them come into your house completely covered in dirt?
If I didn't then they wouldn't come back in... if I do will that destroy an ecosystem, or make agriculture difficult?
Why do you keep your house clean?
Well if you ask my wife, I don't. To keep people healthy would be a reason. The home doesn't have an ecosystem to balance of course. If it did it would be because it was never cleaned.
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.
