Walking down a wide alleyway Friday near the University of Washington, I came upon an upon an unusual sight. In this gritty stretch of loading docks near University Avenue was a scene sprung out of an Ikea catalogue: a long beige couch, funky plastic egg-shaped chairs, lush indoor plants, bouquets of flowers, and a bookshelf with puzzles and Pictionary.

This was an outdoor living room, plenty spacious for a dozen people to hang out. Passersby munched on free sandwiches, chatted, flipped through m…