There's quite a few multinationals that have underseas cables as part of their network infrastructure (think finance). It's sometimes worth the expense just to

There's quite a few multinationals that have underseas cables as part of their network infrastructure (think finance). It's sometimes worth the expense just to lay cable then tunnel through the public internet for peace of mind. On a smaller scale there are plenty of people running long distance microwave networks and paying for direct fiber links that are outside the public internet.