How could modern zombies even take over

Does anyone ever consider that one on one you can stop someone from bitting you? Also with modern drones that cost Pennie’s how can any major Hollywood series even be taken seriously. For cheap they could literally have drones that devastate thousands. Also not to say why wouldn’t the military just have armored vehicles with remote controlled turrets. Zombies seem to be just unarmored people I don’t see how when we have full on intelligent armies to battle a zombie apocalypse would be a challenge. I would even be skeptical of wwz type zombies even being so devastating.