One recent morning, eager to satisfy his breakfast craving, Robert Wunderlich stepped into his Frisco front yard and turned his eyes to the sky. He spotted a small dark object to the north, approaching his home at 35 miles per hour. Soon enough he could make out the boxy shape of an unmanned aerial vehicle—a UAV, or drone—with a delivery company’s name, Flytrex, emblazoned on its side.The model FTX hexacopter came to a halt and hovered 230 feet above Wunderlich’s driveway. Next, as its six blades continued spinning, it descended to a height of about eighty feet before opening doors in the bottom of its payload bay to lower its delicious cargo to the ground on a tether. A hook holding the package then automatically…