I kid you not. Riding the tube in London now costs four pounds, which is equal to $8 US. They hiked up the cash fare to get people to buy the "Oyster" electronic smart card, using which you pay only 1.50 pounds ($3) per ride.
To compare, in Los Angeles, riding the Metro bus or subway is $1.25 per one-way trip. A day pass is only three dollars. Yes, three dollars gives you freedom on L.A.'s transportation system for one whole day. There are certain DASH lines where you have to shell out an extra quarter, but not downtown... maybe it's smiling at the driver that lets me get away with it.