Now why doesn't anyone take a rocket and stick the drone guidance on it? Again I am only guessing here, the drone guidance components probably can't cope with 2-3 mach. At 1000 meters per second with a 60 fps camera you advance 16.6 meters per frame, add to that the latency of whatever guidance system you have. You are looking at 20-30 meters offset between frames.
Better guidance probably balloons the cost to the 10s of thousands of dollars.