You want to buy or sell on Craigslist but worried about meeting up to complete the transaction? Towns are creating safe “exchange zones” with ample lighting and video surveillance to facilitate peer-to-peer commerce. Often in concert with the local police, they’re a fascinating example of the physical world shifting to reflect the needs of the digital one. Are they an aberration while we solve for trust online (craigslist notably lags in this area since they don’t require any real identity in their listings)? Or should each municipality think more deeply about how town squares, libraries and other public institutions can evolve.