On a November trip to Washington, DC. I flew into BWI, took the MARC commuter train to Union Station in DC and arrived after midnight due to train delays. Usually I take the Metro if it's before midnight, so, in this case, there was a very long line at the taxicab curb, and a person who was delegating cabs.

You HAD TO SHARE a cab (don't know if this was a concrete law or whatever, but no one raised a stink) with anyone going in the same direction (National, Georgetown, downtown, Capitol, etc.). The fare was the same, I didn't get a discount, and the delegators put at least 4 people in each cab. I don't know about profit, but it made sense to me...I don't want to be the one at the end of the line if no one shared a cab, I'm tired and just wanted to relax, the amount of gas, time and energy saved is considerable, and everything happened so fast. Better than waiting. BAM, load up, I'm there. Of course, being the short person...had to take the middle seat in the back.