Mom’s Van Is Called Uber

On the first, fine Tuesday in autumn, Guy Parkin, 13, was sitting outside on the steps of the Salk School of Science on East 20th Street. He had stayed late to attend a Specialized High School Admissions Test group study session, so it was nearing 5 p.m. when a black S.U.V. pulled up, dispatched through his mother’s account on the Uber app.