Zillow's big win in the real estate listing wars will create big headaches for homebuyers

Getty Images; Alyssa Powell/BI

Search for a home on Compass.com, the website of America's largest real estate brokerage, and you'll find a familiar layout: a map of available homes, a bunch of price tags, a lineup of shimmering kitchens and golden-hour facades. It all looks a lot like Zillow, the near-ubiquitous home search site.

There is one key difference between Compass' site and Zillow, though: a prominently displayed black box.

Behind the black box sits a heap of listings beyond Zillow's reach...