From Vox and the always brilliant Matthew Yglesias:
How is Houston able to pull that off with no additional funding? Well, as Jarrett Walker, one of the plan's lead designers, explains it's all about prioritizing rides that will plausibly attract riders. The old system, like many bus routes in the United States, expended a lot of resources on very low-ridership routes for the sake of saying there's "a bus that goes there." The new plan says that the focus should be to provide reasonably frequent service on routes where reasonably frequent service will attract riders. That does mean that some people are further than ever from a transit stop. But it means that many more Houstonians will find themselves near a useful transit stop.