Wpeotih:

well he does mention parking and being off a highway, and it's clearly a huge congregation, so it seems reasonable to assume that at least some people are driving to this place from somewhere else.

It's not reasonable to assume those people are from "the exurbs." Everyone in Houston drives.* Some people might even be driving in from their downtown lofts--for all we know. People might be sitting in high-rise apartments watching Joel Osteen.

*except for small children and people who don't have at least $1K for a beat-up car.