Walking around the Upper East Side, where I live, I find it striking how many of the establishments still standing among the many darkened windows are hair salons, nail salons, facial salons, eyebrow places, and restaurants. What’s the one thing they have in common? You won’t find their services on Amazon. The internet won’t cut my hair, and not even the most homesick midwesterner goes online to order a deep dish to be delivered from Chicago to New York. Online shopping has digitized a particular kind of business — mostly durable, nonperishable, and tradable goods — that one used to seek out in department stores or similar establishments. Their disappearance has opened up huge swaths of real estate.