If you operate a movie theatre, you can't check passports on the door and only allow citizens of a specific country to enter.
True, but you can be pretty certain that someone coming in to your movie theater is physically located in your country. It's also a reasonable assumption that it's legal for them to be there.
You can't stop someone sending physical media across borders, although the north koreans keep trying.
Maybe you can't achieve perfect enforcement, but I would guess that every country in the world has laws about what physical items can be brought into or sent out from that country.
Refusing to sell content to someone based on their location or nationality should be illegal as it's discrimination. Similarly, trying to carve the world up into arbitrary areas so you can enforce exclusive distributors in each area is anti-competitive and should also be illegal.
I agree that that's a great ideal. The problem is, under who's jurisdiction? For example, the United States has very little control over what companies do in other countries (openly, anyway; I'm sure there's plenty of military and economic threats being passed around back channels), nor can the United States force companies from other countries to sell in the United States. You would need either an international treaty, which the media companies would never allow, or a world government with this kind of authority, which the UN is unlikely to get any time soon.