What makes you think we can’t shoot Shaheeds at 100km distance? The operational envelope of Eren states, 100+ km engagement range.I know that there is a range limitation, but for Shaheds specifically, it wouldn’t matter. I don’t think that we can shoot Shaheds 100 of Km away anyway.
The turbojet engine that propels it is supposed to give it fairly high speed. It can sustain this speed for 15+ minutes. At 600km/hr speed that means 150+ km range. At 400km/hr it means 100km range.
Shaheed drones travel at 180km/hr. Eren could easily run after it and catch it up. But in most cases it will probably go for it head on, which will increase the engagement range.