Buses often fall down on the job—not because they’re buses, but because they’re slow. Buses are slow in part because city leaders don’t want to slight anyone and thus end up having them stop far too frequently, leaving almost everyone worse off. Buses also tend to feature an inefficient boarding process. Having each customer pay one at a time while boarding, rather than using a proof-of-payment where you pay in advance and then just step onto the bus, slows things down. That can generate a downward spiral of service quality where slow speeds lead to low ridership, low ridership leads to low revenue levels, and low revenue leads to service that’s infrequent as well as slow. Closing the loop, a slow and infrequent bus will be patronized almost exclusively by the poor, which leads to the route’s political marginalization.

Worst of all, even though a bus is a much more efficient use of crowded space than a private car, it ends up stuck in the same traffic jam as everyone else.