PHILADELPHIA — The men gathered in front of the BZ Ballaz Club barbershop in a gritty, mostly Hispanic section of north Philadelphia were listening intently as Kimberly Cromer made her pitch for a career in long-haul trucking.Faced with what trucking experts describe as the worst labor shortage in the industry's history, recruiters like Ms. Cromer are canvassing cities and holding job fairs to entice new drivers. With predictions from the association that the current shortage of 20,000 drivers will grow nearly fivefold within a decade, trucking companies are offering generous 401(k), stock option and health care packages to new...