THE HAND-OFF Angela Kim’s baby-sitting routine: On Tuesdays her husband, Augustine, drops her off at a Houston airport. She’s met at the curb in Dallas by her daughter, Andrea, and her son, Noah, 2. Then it’s off to the hospital where Andrea works, where Mrs. Kim takes the wheel. She heads for Noah’s preschool and after that, home for a nap. On Wednesday nights she makes the reverse commute.