Thanks to technology, no one has to wait in line anymore. Some people do it anyway.

Every day, Mitchell Burton orders and pays for an Italian B.M.T. sandwich on his Subway mobile app, so the sandwich is waiting at the counter. When he arrives, the 32-year-old Baton Rouge, La., parks and recreation worker frequently heads to the back of the line, to avoid seeming rude to less tech-savvy fellow customers.

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