Why can't people move down inside the carriage?

So, the London Underground. It's actually great, by and large. It gets you there, it runs extremely often, it's clean, etc., etc.

However. The people on it just do not understand that you have to move away from the doorway so that other people can get on the train. If you do not do this, there are awkward queues at the doors and the train operator gets cross. Which is not really fair, because you can't predict that the people in front of you are morons before you get in the queue.

And, no, this does not make it impossible to get off at your stop. Because, you see, if people at the doorway are not packed in an immovable mass, you can pass through them with minimal difficulty.

There is also the added bonus that you are not necessarily smushed directly against ninety-three other people.

Figure it out, London.