What advantages would a tank have over a drone which could hover in place and has pin-point accuracy with a controllable blast radius?
As in a theoretical drone that's practically an attack helicopter without the worry of too much collateral damage.
As far as I can tell it would be able to do everything a tank with added mobility
Can't jam a tank. Until a decent AI is developed, unmanned weapons will be limited in use.
This is true. I do wonder why they don't seem to ever deploy dumb munitions on UCAVs...
I don't know how to answer questions like this.
It's akin to asking why should I use a shovel to dig a hole when I can use a hammer.
Each tool is designed to fill a role.
If you really are interested understanding the answer you should look up what's the purpose and role of the tank in conventional warfare and in counter insurgency warfare.
What purpose does it fulfill on defense and offense.
When you read that up, you can ask more specific questions.
Can't we use a drone to fill function X a tank has and which does it better.
I would look up what types of armament a tank carries (or at least capable of carrying).
The main gun is not it's only weapon and there are different types of projectiles for different missions.
Just a few obvious things:
A tank has machine guns, usually 7.62 and 0.5 cal for close support. You can't fit that on a drone with nearly the same amount of ammo and this drone is getting really huge.
The number of shells a tank can carry vs how many a drone can.
point of view - an eye in the sky doesn't see the same things an eye on the ground does. Neither is better, but help each other.
What happens when there is a malfunction, drone has to leave (at best) or falls from the sky.
The tank is still there to provide support. It can function very well (with a capable crew) even with some malfunctions (communication, fire support and so on, I am not a tanker so I wouldn't be able to give a complete view).
And so on.
You're basically saying
>Why use tanks when you could use unmanned attack helicopters?
The answer is that tanks can carry more munitions and function for longer before they need supplies. They're also a lot more heavily armored.
Considering the similar roles of tanks and attack helicopters yet their continued coexistence in modern militaries, they are different enough that none is superior to the other.