Kirk Gallegos is a single father of four. He works construction in Barstow, Calif. Prudence Carter is a single mother of one. She's the dean of the Graduate School of Education at the University of California, Berkeley. Both share the same problem with tens of millions of other parents around the country: Their public schools aren't operating full time in-person this fall. And the rest of the child care system, which had been stretched even before the pandemic, is itself under pressure. The...