Simple solution
Why don't they simpy feed the datastream from accoustic sensors, signal triangulation, radar, lidar, IR and optical sensors on ground-based and high-altitude observation platforms into a neural network trained to detect drones, and present the results as tracks on a map?
Then all they have to do is go to the take-off point, tazer the operator and take control of the drone, or if they are not there, vaporize it with a laser or microwave beam. Job done, what is so difficult about that?
OK I am joking, but some of these elements could be developed to protect airports and other key installations from drones in the future?