[sowbug]

When I was a kid and tried to figure out why this fare/penalty existed, I guessed it was to compensate for people who traveled somewhere to pick up an item from a friend who'd meet them at the station and hand it through the gate to them, and then they'd go back home, all without leaving the station. It all seemed like an intricate solution to a small problem.

[tedunangst]

What makes it intricate? There's a big table of station x station fares. Filling the diagonal with $6 is no more complicated than filling it with $0.

[sowbug]

You're thinking from an implementor's perspective. From the customer's perspective, it's a weird nonlinear pricing model that charges you more to be taken a shorter distance. Honest people who forgot their keys at home or whatever and need to run back home have to deal with the nonlinearity.

[flomo]

In ye olden days, my company had a courier who would shuttle interoffice mail between the Walnut Creek and downtown SF offices on BART all day. So I could see this happening.