Is there a reason that these use batteries rather than combustion engines?
Are you expecting the drones to use hardened GPS modules resistant to hijacking and not get DDoS'd by someone broadcasting fake GPS at their take off area?
I have been working on my quads since 2011 and have three.
Aside from their main downside (energy density), which is improving each year and now reaching 265 Wh/g, electric batteries provide many improvements. First of all, electric motors are more efficient than gas-powered motors. Secondly, gas-powered motors are fairly heavy, so you need a bigger and thus more expensive quadcopter. Thirdly, it is difficult to control a gas-powered quadcopter at the speed of an electric quadcopter.
TL;DR It's possible but difficult to make a gas-powered quadcopter, since it'll be heavy and difficult to control. At that point, it doesn't make much sense to use a quadcopter, since two of their biggest advantages are how easy they are to control and how light they can be.
Also, it would make no sense for you to "DDoS" a GPS module. DDoS = distributed denial of service. You're probably thinking of jamming (broadcasting garbage data so the GPS can't receive anything) or spoofing (broadcasting fake data.)
> Thirdly, it is difficult to control a gas-powered quadcopter at the speed of an electric quadcopter.
I disagree with you there. Collective pitch quadcopters with combustion engines have been done. With CP quads you lose one benefit of traditional quadcopters, which is their simplicity (basically, they're four electric motors with a computer that tells each one how fast to spin), but that benefit is more applicable to hobbyists than to commercial package delivery.
Ease of use, complexity and reliability. I'm referring to drones < 10kg. There's a point in large systems where gas becomes a more competitive option but for smaller multicopters it's not.
Are you expecting the drones to use hardened GPS modules resistant to hijacking and not get DDoS'd by someone broadcasting fake GPS at their take off area?