David Cantrell wrote:
If you've already spent umpty hundred pounds on getting to London and
accomodation in London, I suggest that worrying about the odd penny here
and there on your tube tickets is just not something that a rational
tourist will do. They'll care that they have a valid ticket, not that
they have the most efficient possible ticket.

Let them eat cake?

Not everyone is visiting on business from the USA and staying in a Zone 1
hotel. Some people are coming on the coach from the continent and staying
in a hostel. Some people are flying to Europe and spending months
travelling with a tight daily budget. Some people are sleeping in a tent or
a camper van. A family may be sharing a small hotel room in zone 6.

Just because you've come to London doesn't mean you have money to spare, in
the same way that living in London doesn't automatically mean you are rich.

Theo