Why does the cursor stay visible in some demos I've played?

I haven't started learning Unity yet, but I really want to know the answer to this question before I start.

In this "Tropical Paradise" demo, the cursor stays visible the whole time you're playing, which is incredibly annoying.

http://unity3d.com/gallery/live-demos/tropical-paradise

I've tried other small Unity projects that have the same problem. Like Red Sky, a small project by the indie dev who made VVVVVV.

http://distractionware.com/games/unity/redsky/

This couldn't have possibly been done by accident, could it? Can someone tell me why the cursor stays visible in these? I tried another official demo that didn't have this problem.

To hide the cursor, you need to use `Screen.showCursor = false`.

The cursor is probably still visible in the webplayers you listed because this was not used inside the game.

I am not sure but, It is probobably because someone did not kill the resource properly.