Transit ridership rises nationally, drops in the DC region
According to "Use of public transportation jumps" from the Los Angeles Times, transit ridership is increasing nationally, likely in response to tighter household budgets, gasoline price increases, etc., using the most recent data from the American Public Transportation Association. Ridership is up 2.6% nationally, and a bit less, under 2% in Los Angeles.
But after raising fares last year, WMATA reports ("Metrorail ridership drops 5 percent below agency's target" from the Examiner) that ridership has dropped. Also see "If not Metro fare increases, what does it take to unite riders?" from the Post's Dr. Gridlock column.
The WMATA system is an odd combination of a local railroad commuter system and subway system and has a fare structure more like railroads, based on distance, whereas most other subway and light rail systems have lower average fares that are not distance based.
Typically systems charge a flat fare ranging from $1.50 to $2.50, with the exception of the BART system in the San Francisco Bay area, which is set up the same way as the WMATA system, and surprisingly has higher maximum fares (+ surcharges to go to the San Francisco International Airport and to go through the Transbay Tube) but a slightly lower base fare and they don't charge different prices for peak-time vs. off-peak service (they also have about half the ridership of the WMATA system).
Most other transit systems have a less complicated fare structure and flat fares (although they may charge an additional fee for a transfer). Some systems have an all-day pass, some don't, and most offer weekly and monthly passes that provide discounts as well.
Plus, WMATA's regular weekend track maintenance programs seriously discourages people from using transit then, because the service becomes less efficient and much less reliable.