Angel Rodriguez learned how to detail cars on YouTube. After school and late at night after work, he studied videos that explained arcane matters like the ideal brush length to maximize the performance of a rotary polisher and the best techniques to power-wash a grungy car until it gleamed.
Mr. Rodriguez, a 21-year-old car aficionado, has worked the checkout counter at Toby’s Feed Barn for the past three years. When his shift ends, he…