My 16-month-old son was having a bad day. When he doesn’t sleep in the car, he usually points and babbles his approval of all the wonderful things babies notice that completely escape adult attention. On this afternoon, though, he was teething and hungry, a lethal scenario for an energetic youngster strapped into a high-tech seating apparatus (approved and installed, of course, by the state). When it became clear he couldn’t, or wouldn’t, sleep it out, my wife and I stopped at a nondescript exit, the kind one finds every six miles in the South, with two gas stations and three...