Amazon CEO Jeff Bezos is known for his laser-sharp focus on a few things: speedy delivery, the lowest prices, and a willingness to forgo profits in the short-term to ensure them both.

This combo has proved brutal for competitors. Look at what just happened this week. Flipkart, an e-commerce site based out of India, announced it had raised $1 billion in funding. The next day Jeff Bezos announced plans to invest $2 billion to expand Amazon in India.

So when Bezos announced plans to invest in drones that could plop packages on customer doorsteps in 30 minutes or less late last year, it seemed like he was once again trying to intimidate the competition — if not just to get some publicity.

But what many people missed last year has become increasingly obvious this year. Amazon needs drones because same-day delivery is quickly becoming a competitive advantage for Amazon's rivals. If Amazon really plans to achieve the holy grail of same-day delivery, it might have no choice but to try something like drones. In short, Bezos wasn't joking.

The hyper-fast delivery space is already crowded. Google recently launched Shopping Express for same-day deliveries in New York and Los Angeles. eBay Now started making local deliveries nearly two years ago. Walmart To Go will deliver your groceries right to your door. Smaller startups — like Instacart, Postmates, and WunWun — give customers the option of getting anything instantly.

Amazon already offers more than 500,000 different items for same-day delivery in 12 metropolitan areas. Amazon Fresh, its grocery-delivery program, serves only California and Seattle. Ideally, it would be able to offer rush delivery for almost everything to almost anywhere.

But the logistics of a same-day delivery model sustainable are complicated (just ask Kozmo or Webvan, two flame-outs from the dot-com boom). Bezos tested Amazon Fresh in Seattle for five years before daring to expand the program to L.A.

Amazon has already been taking the delivery process more into its own hands by investing in a delivery fleet more spread-out fulfillment warehouses, and 16 new "sortation centers" to make shipping more efficient. While Fed-Ex or UPS may be too slow for Amazon's tastes, however, immediately deploying big trucks to every address for every customer order would be unfathomably expensive. That's why Amazon needs drones.

"They are leveraging logistics," Adrian Gonzalez, president of supply-chain and logistics company Adelante, told Business Insider. "Drones are another piece of the puzzle. It's not going to be the right solution for every scenario, but for certain scenarios. The whole idea here really is the ability not to lose a sale because you can't get something to the customer when they want it."

Right now, Amazon charges $8.99 per delivery, plus 99 cents for each item shipped (or $3.99 with a gift card) for its same-day delivery service. But even with this premium it's still expensive.

When Bezos introduced the drone-delivery concept, the subtext was that it would make sense only if it saved the company money. In 2013, shipping cost Amazon $6.63 billion. Over the past three years combined, the net cost of shipping has been about $8.8 billion. That's a lot of money.

Would drones give Amazon a cheaper delivery alternative? It's difficult to say right now because drone technology is still new and there is no precedent for a retail company with deep pockets like Amazon investing in drones for delivery.

However, RobotEconomic's Colin Lewis did some back-of-the-napkin math to figure out whether drones could save Amazon some cash. His conclusion: yes. He believes Amazon's average shipping cost is $2 to $8. With drones, if Amazon prices it right, the cost could be as low as $2 a shipment.

(Not to mention the reduced carbon emissions from delivering via drone instead of truck. "It’s very green," Bezos said during the announcement. "It’s better than driving trucks around.")

To make the complicated, costly logistics of same-day delivery worth it, Amazon needs to know that its huge investment will lead to increased sales.

Drones definitely play a role here. Right off the bat, the novel nature of getting a package delivered in 30 minutes or less by a futuristic-looking drone would likely reel in some curious consumers. They might buy a product offered by Prime Air just for the experience.

"This is another arrow in Amazon's bow to set themselves apart from the rest of the retail industry," Gonzalez says.

But it goes deeper than thrill seeking. In a 2013 study, Amazon proved that speedier shipping leads to more purchases. In a test with Prime customers, the company found that even just displaying an icon promising same-day availability increased the likelihood of purchase by between 20% and 25%. (Interestingly, though, most ended up choosing next-day delivery instead of same-day.)

If that trend carries, Amazon could see an even greater increase in purchases if it can an offer Prime Air shipping on a bunch of products.

Of course, there are a bunch of ways that Amazon could deploy its drones. In Bezos' original demo video, he showed one zooming off from an Amazon warehouse. Gonzalez theorizes, however, that Amazon could also reach more diverse areas farther away from its fulfillment centers by packing 30 to 50 loaded drones on a truck, driving them to a central location, and then deploying from there.

Right now, Amazon is testing the eighth and ninth generation versions of its drones in its research and development lab in Seattle. Unfortunately for the company, commercial drone use is currently illegal. Federal Aviation Administration rules dictate that only hobbyists can fly small unmanned aircraft systems (sUAS) outdoors, while all commercial experimentation needs to take place inside. On July 9, Amazon filed an exemption request with the FAA asking for permission to test its drones outside.

The administration has to come up with a plan for “safe integration” of commercial drones by Sept. 30, 2015, though it plans to release proposed rules for small drones under 55 pounds later this year. Once it comes up with that set of rules, they'll be submitted for public comment, and then reviewed again before they're finally enacted. Even then, Amazon and others might have to keep waiting. "Safe integration will be incremental," the FAA writes

To its credit, the FAA isn't trying to be the bad guy.

"You have to appreciate the magnitude of what it is we are trying to do," FAA media representative Les Dorr, told Business Insider. "We're writing rules that will apply to the most complex, busy airspace in the world. We're trying to meet our overriding goal of avoiding safety hazards but at the same time we don't want to put an undue regulatory burden on an emerging industry."

For its part, Amazon argues that it should be allowed to start testing outside so that it can be completely ready to implement its drones once the FAA makes commercial flight legal.

"Amazon always try to be one step ahead of the competition with everything they do," Gonzalez says. "This is them pushing the envelope, for providing another way to deliver packages in a very short time period."