Considering the multitude of different Zombie movies i shall give a few reasons.
1. Zombies are toxic. Zombies only react to warm flesh. The virus/parasite responsible for reanimating said Zombie will only attempt to continue it (virus/parasite) survival therefore will not attack other Zombies as in each Zombie is a multitude of itself.
2. I believe that Zombies only have basic instinct of survival i.e. to feed. Hence only those senses needed to accomplish this goal should be active i.e. called efficiency. For fast crazy 28 weeks later zombies they are consistently angry hence adrenaline which blocks pain.
3. The only fast Zombies are technically still alive. Even in resident Evil particularly 5 the fast Zombies are due to a virus manipulating brain function and inducing other physical qualities.
4. Err... Resident Evil 5... And generally in other media depicting Zombies it is usually used as a biological weapon. Placed to just cause shit load of damage and death :S.
5. And no. Should read into it more and try answering your own questions.
1. Zombies are toxic. Zombies only react to warm flesh. The virus/parasite responsible for reanimating said Zombie will only attempt to continue it (virus/parasite) survival therefore will not attack other Zombies as in each Zombie is a multitude of itself.
2. I believe that Zombies only have basic instinct of survival i.e. to feed. Hence only those senses needed to accomplish this goal should be active i.e. called efficiency. For fast crazy 28 weeks later zombies they are consistently angry hence adrenaline which blocks pain.
3. The only fast Zombies are technically still alive. Even in resident Evil particularly 5 the fast Zombies are due to a virus manipulating brain function and inducing other physical qualities.
4. Err... Resident Evil 5... And generally in other media depicting Zombies it is usually used as a biological weapon. Placed to just cause shit load of damage and death :S.
5. And no. Should read into it more and try answering your own questions.