To expand a little bit, RF is subject to free space path loss - signal strength decreases proportional to the square of the frequency and the square of the distance. The higher the frequency, the less far you go. Of course, weaker signals are harder to distinguish from noise so there’s only so weak your signal can go. If you want to control drones, lower frequencies are better.

There’s a reason that microwaves (the cooking instrument, named after the rough band of RF frequencies it uses) interfere with WiFi when improperly shielded: they run at approximately 2.4GHz. That’s a part of the band that’s free to use without licensing (ISM band, runs at 900MHz, 2.4GHz, 5Ghz, and so on). That’s because microwave manufacturers don’t want to license spectrum, and it’s the part of the ISM band closest to the ideal absorption frequency of water. The point of microwaves is to push energy into water molecules and make them move around faster, aka heat them. Water molecules do that well at 2.4GHz. This also means that water blocks RF at that frequency very well, because it absorbs it. Trying to shoot 2.4GHz WiFi through trees sucks because it gets blocked by the leaves.

So you want to control drones. You can’t be around 2.4GHz because rain would screw you up. You can’t go above that so you can get enough distance. You can’t go as low as 900MHz or other stuff on the ISM band might interfere with you.

Not that much left, given that 1.7GHz is a popular cell phone frequency, and so on - you can look at publicly available frequency charts to see what’s assigned for what where.

This glosses over a lot and is heavily simplified.