NEW YORK—Starbucks Corp.’s newest cafe lacks one element most customers are used to seeing: cashiers. The global coffee chain on Thursday opened its first ever location in partnership with Amazon Go, the e-commerce giant’s brick-and-mortar convenience store, where customers can sit at a table with a latte or grab a sandwich from a shelf and walk out. Hit by a U.S. labor crunch, Starbucks and other companies are expanding labor-saving technology like artificial intelligence, robotics, and digital touch screens. White Castle is testing a robotic fry cook and Domino’s Pizza Inc. is experimenting with self-driving vehicles for delivery. IBM is developing automated order taking for McDonald’s Corp. drive-thrus. U.S. restaurant staffing levels broadly are still at least 10 percent lower than before the pandemic, helping boost margins, said Rabobank analyst Tom Bailey. “You’d see some of the digital automation tools deployed to cover that 10 percent gap as they grow,” …