That's like me going up to a Netflix engineer and saying "why do you get paid so much? You've got the video already, just send it to the device; shouldn't be much of a problem."
Well, the difference would be that I actually built radios, and at least some of them worked. It's really that simple, even without SDR. You already have a microcontroller that reads rotary encoder attached to the tuning knob and changes voltage that goes to the VCO (or divisor in PLL). All you need is to control it from CSPRNG.
You will need to spend some effort on getting synchronization right, but it's a lot less complicated than, say, building a CRUD app.
Congratulations, you made a few working radios with the most basic feature set.
Now make a radio that works in sub-zero and 100+ degree temperatures, survives water, dust, and firearm exposure, being dropped dozens of feet, is resistant to broad-spectrum jamming, can handle secure encrypted communications with a large set of ever-changing participants, has a range of dozens of miles and days of battery life, is of a size and weight portable enough to be carried by a soldier for hours or days alongside their normal gear, and which can be field-repaired by a soldier with a few days of training.
And those are just the high-level requirements. It's a lot more complicated than a CRUD app, which even a non-programmer can do in an hour.
The application portion has a nice explanation on the effects of gun fire on systems. Keep in mind that "gunfire" covers everything from a 9mm handgun to a 30mm Gatling gun.
I was talking about the tactical radios discussed in the article (2km range).
If you want the radio to let you watch video feed from a drone above, show a map with locations of other soldiers, or update Facebook status via satellite link, that may be a bit more work.
