Cash fares within Greater London must be the most expensive in the UK. It seems rediculous to charge £4.90 for a Single or charge £9.80 for a Return for a journey of just one stop such as Moorgate to Old Street.
I'm sure there are bus fares more expensive per mile outside London - and even inside London.
£10 a mile is pricey. Altrincham to Navigation Road is £3.28 a mile, Deansgate to Oxford Road is £4.68 a mile.
On the metrolink, Picadilly Gardens to Market Street is £7.60 a mile. If you choose to pay the standard fare of £100 that increases to £715 a mile.
But short trips on metro services are always an anomaly, and it's very unlikely anyone would ever make such a trip, and even if they did in London they'd simply pay the oyster fare.