To date, e-commerce has been about scale. But when it comes to same-day or even same-hour delivery, the economics become tricky, regardless of how many units a company sells. Loss leaders like Amazon reign supreme as they stamp out competition, but profitability has been an elusive benchmark in the ultra-fast delivery wars. That's doubly true for grocery delivery, which is a logistical nightmare of temperature zones and handling constraints. Automation will certainly play a key role in making lightning fast grocery delivery profitable, but one company, CommonSense Robotics, believes another part of the equation is to think small.