They make hand helds that can be used without human LOS with something like 3km range. You don’t definitely need automated systems but obviously that would be probably more bullet proof.
It is but I would hope these entities are trying at least something and those jammers are cheap.
In Paris they developed an electronic barrier wall for drones. Yes maybe these are autonomous enough that when the link is cut they continue on their mission but I think something is better than nothing.
The bigger issue I assume is probably that even if you react very quickly the drone might be already gone already anyway.