And I remember trying to buy a tube ticket from a machine where the first thing you have to enter is your 'zone'. How am I supposed to know what zone I'm in ? And I only discovered by accident after several visits that having bought a DLR ticket from the City airport I didn't need to buy a second ticket when I joined the tube. How are you supposed to know these things ?
If you have a 'contactless' credit or debit card, you can use that. Then there's no need to buy a ticket or Oyster Card for London transport. What is good about that is that you will only be charged the maximum daily rate if you do a lot of journeys and changes.
Oh yes, most escalators (all on the underground) do have a sign saying 'keep right'