Up until now, Amazon’s planned delivery-by-drone service was only able to undergo tests indoors — or in other countries. But the biggest regulatory hurdle holding back the company was removed yesterday when the FAA issued an “experimental airworthiness certificate” for the company's drone program, allowing Amazon to legally test its unmanned aircraft in the free and open air of the United States.

Now American airspace is fair game, provided the drones fly no higher than 400 feet, only during the day, and are always in sight of the person manning the controls, who must be a certified pilot.

If this gets you excited about the future of robot-based delivery, you should probably read that list of requirements again. The last in particular illustrates just how far Amazon has to go before its drones can really get to work. It's not just because a licensed pilot has to control the drones (though that’s certainly limiting). The real restriction is that there must be a person at the controls at all. All along, Amazon has planned for drone delivery to be autonomous, with packages buzzing through the sky thanks to flying robots and their robot brains.

Restrictive as it is, the FAA ruling may be the least of the worries for Amazon and the rest of the companies hoping to get in on drone delivery, according to a report in today’s Wall Street Journal. Drones still have heavy, inefficient batteries, an inability to deal with bad weather, and an over-reliance on shaky GPS. What’s more, even if a drone makes it to the right place without incident, no one has figured out how to get a package down to a person. Ideas include dropping them on a porch and lowering them by a rope.

And, once a company gets past all those challenges, there’s a final problem to solve: how to convince the gun-toting, drone-hating Ron Swansons of the world to accept their deliveries.